Assault Rifle ” M4 SOPMOD II “

SOPMOD Block I

SOPMOD (Special Operations Peculiar Modification) Block I

U.S. Special Operations Command (USSOCOM) developed the Special Operations Peculiar Modification (SOPMOD) Block I kit for the carbines used by units under its jurisdiction. The kit features an M4A1, a Rail Interface System (RIS) handguard developed by Knight’s Armament Company, a shortened quick-detachable M203 grenade launcher and leaf sight, a KAC sound suppressor, a KAC back-up rear sight, an Insight Technologies AN/PEQ-2A visible laser/infrared designator, along with Trijicon’s ACOG TA-01NSN model and Reflex sights, and a night vision sight. This kit was designed to be configurable (modular) for various missions, and the kit is currently in service with special operations units.

SOPMOD Block II

M4A1 SOPMOD Block II in Afghanistan 2012

A second-generation SOPMOD kit (now known as SOPMOD II) includes innovative optics, such as the Elcan Specter DR, Trijicon’s ACOG TA01 ECOS model, and the Eotech 553. Block II uses the RIS II rails manufactured by Daniel Defense in both a 9.5 and 12.5 length.

Variants

Except for the very first delivery order, all U.S. military-issue M4 and M4A1 carbines possess a flat-top NATO M1913-specification (Picatinny) rail on top of the receiver for attachment of optical sights and other aiming devices — Trijicon TA01 and TA31 Advanced Combat Optical Gunsights (ACOG), EOTech 550 series holographic sights, and Aimpoint M68 Close Combat Optic (M68 CCO) being the favorite choices — and a detachable rail-mounted carrying handle. Standards are the Colt Model 920 (M4) and 921 (M4A1).

Variants of the carbine built by different manufacturers are also in service with many other foreign special forces units, such as the Australian Special Air Service Regiment (SASR). While the SASR uses weapons of essentially the same pattern built by Colt for export (Colt uses different models to separate weapons for the U.S. military and those for commercial/export purposes), the British SAS uses a variant on the basic theme, the Colt Canada (formerly DiemacoC8SFW.

M4 MWS (Modular Weapon System)

M4 MWS (Modular Weapon System) shown with various accessories including M203 grenade launcher, RIS foregrip, removable carry handle/rear sight assembly, AN/PEQ-4laser system, M68 CCO reflex sight, and the AN/PVS-4 night vision optics

Colt Model 925 carbines were tested and fitted with the Knight’s Armament Corporation (KAC) M4 RAS under the designation M4E2, but this designation appears to have been scrapped in favor of mounting this system to existing carbines without changing the designation. The U.S. Army Field Manual specifies for the Army that adding the Rail Adapter System (RAS) turns the weapon into the M4 MWS or Modular Weapon System.

M4A1

M4A1 with TA01NSN ACOG 4×32 optical sight

The M4A1 carbine is a fully automatic variant of the basic M4 carbine intended for special operations use. The M4A1 was introduced in May 1991, and was in service in 1994. The M4A1 has a “S-1-F” (safe/semi-automatic/fully automatic) trigger group, while the M4 has a “S-1-3” (safe/semi-automatic/3-round burst) trigger group. The M4A1 is used by almost all U.S special operation units including, but not limited to, Marine Force ReconArmy RangersArmy Special ForcesNavy SEALsUnited States Air Force Pararescue and Air Force Combat Control Teams. It has a maximum effective range of about 500 to 600 meters (550–660 yd).[7] The fully automatic trigger gives a more consistent trigger pull, which leads to better accuracy.[37] According to Mark A. Westrom, owner of ArmaLite, Inc., automatic fire is better for clearing rooms than burst fire.[38]

In the last few years, M4A1 carbines have been refitted or received straight from the factory with barrels with a thicker profile under the handguard. This is for a variety of reasons such as heat dissipation during full-auto, and accuracy as a byproduct of barrel weight. These heavier barrel weapons are also fitted with a heavier buffer known as the H2. Out of three sliding weights inside the buffer, the H2 possesses two tungsten weights and one steel weight, versus the standard H buffer, which uses one tungsten weight and two steel weights. These weapons, known by Colt as the Model 921HB (for Heavy Barrel), have also been designated M4A1, and as far as the government is concerned the M4A1 represents both the 921 and 921HB.

Conversion of M4s to the M4A1 began in 2014, the start of all U.S. Army forces being equipped with the automatic variant.[39] Though in service with special forces, combat in Afghanistan showed the need for providing automatic suppression fires during fire and movement for regular soldiers. The 101st Airborne Division began fielding new-built M4A1s in 2012, and the U.S. 1st Infantry Division became the first unit to convert their M4s to M4A1-standard in May 2014. Upgrades included a heavier barrel to better dissipate heat from sustained automatic firing, which also helps the rifles use the M855A1 EPR that has higher proof pressures and puts more strain on barrels. The full-auto trigger group has a more consistent trigger pull, whereas the burst group’s pull varies on where the fire control group is set, resulting in more predictable and better accuracy on semi-automatic fire. Another addition is an ambidextrous selector lever for easier use with left-handed shooters. The M4-M4A1 conversion only increases weapon weight from 7.46 lb (3.38 kg) to 7.74 lb (3.51 kg), counting a back-up iron sight, forward pistol grip, empty magazine, and sling. Each carbine upgrade costs $240 per rifle, for a total cost of $120 million for half a million conversions. 300 conversions can be done per day to equip a brigade combat team per week, with all M4A1 conversions to be completed by 2019.[40][41]

Mark 18 CQBR

An M4A1 with a Close Quarter Battle Receiver. The barrel length is 10.3 inches.

The Mk 18 Close Quarters Battle Receiver is an M4A1 with a 10.3-inch barrel upper receiver.[42] Current contractors for the Mark 18 are Colt and Lewis Machine & Tool (LMT) NSN 1005-01-527-2288.

Enhanced M4

For the Individual Carbine competition, Colt submitted their Enhanced M4 design, also known as the Colt Advanced Piston Carbine (APC). The weapon has a suppression-ready fluted barrel, which is lighter and cools better than previous M4 barrels. It is claimed to have “markedly better” accuracy. To improve reliability, Colt used an articulating link piston (ALP), which “reduces the inherent stress in the piston stroke by allowing for deflection and thermal expansion”.[43] In traditional gas piston operating systems, the force of the piston striking the bolt carrier can push the bolt carrier downwards and into the wall of the buffer tube, leading to accelerated wear and even chipped metal. This is known as carrier tilt. The ALP allows the operating rod to wiggle to correct for the downward pressure on the bolt and transfers the force straight backwards in line with the bore and buffer assembly, eliminating the carrier tilt. This relieves stress on parts and helps to increase accuracy.[44] The Individual Carbine competition was canceled before a winning weapon was chosen.[37]

Colt Commando

Though Colt has focused its attention on carbines with 14.5-inch barrels and rifles with 20-inch barrels, Colt continues to make carbines with 11.5-inch barrels, which it calls Commandos. The Colt Model 733, is their first design, and it was made in 1987. It was referred to as the M16A2 Commando, and later the M4 Commando. Unlike the XM177, the Colt Commando was a shorter variant of the M16A2. Originally, Commandos were assembled from whatever spare parts are available, so Model 733 Commandos could have A1-style upper receivers with case deflectors or A2-style upper receivers, and M16A1-profile 1:7 or M16A2-profile 1:7 barrels. Depending on the specific models, Commandos may have had three-position fire control groups (safe/semi-automatic/three-round burst), or four-position having both full-automatic and burst. The modern Model 933 has a “flattop” receiver, with a removable carrying handle and a MIL-STD-1913 Picatinny rail, with semi-automatic and automatic fire. The Model 935 Commando has the features of the Model 933, but has three-round burst fire instead of automatic. Though originally called the M16A2 Commando, Colt markets them as the M4 Commando around 1995.

Armwest LLC M4

In 2014, American firearms designer Jim Sullivan provided a video interview regarding his contributions to the M16/M4 family of rifles when working for Armalite. A noted critic of the M4, he illustrates the deficiencies found in the rifle in its current configuration. In the video, he demonstrates his “Arm West LLC modified M4”, with enhancements he believes necessary to rectify the issues with the weapon. Proprietary issues aside, the weapon is said to borrow features in his prior development, the Ultimax. Sullivan has stated (without exact details as to how) the weapon can fire from the closed bolt in semi-automatic and switch to open bolt when firing in fully automatic, improving accuracy. The weight of the cyclic components of the gun has been doubled (while retaining the weapon’s weight at less than 8 pounds). Compared to the standard M4, which in automatic fires 750-950 rounds a minute, the rate of fire of the Arm West M4 is heavily reduced both to save ammunition and reduce barrel wear. The reduced rate also renders the weapon more controllable and accurate in automatic firing.[45]

Performance

A U.S. Navy sailor fires an M4 carbine from the warship USS Vella Gulf.

The M4 carbine has been used for close quarters operations where the M16 would be too long and bulky to use effectively. It has been a compact, light, customizable, and accurate weapon. This has come at the cost of reliability and maintainability. Failure to maintain the M4 causes malfunctions. This became apparent as it saw continued use in the sandy environments of Iraq and Afghanistan.[46] Despite this, in post-combat surveys, 94 percent of soldiers rated the M4 as an effective weapons system.[47]

Early feedback

By late 2002, 89 percent of U.S. troops reported they were confident with the M4, but they had a range of problems. 34 percent of users said the handguards rattled and became excessively hot when firing, and 15 percent had trouble zeroing the M68 Close Combat Optic. 35 percent added barber brushes and 24 percent added dental picks to their cleaning kits. There were many malfunctions, including 20 percent of users experiencing a double feed, 15 percent experiencing feeding jams, and 13 percent saying that feeding problems were due to magazines. 20 percent of users were dissatisfied with weapon maintenance. Some had trouble locking the magazine into the weapon and having to chamber a round in order to lock the magazine. Soldiers also asked for a larger round to be able to kill targets with one shot. New optics and handguards made usage of the M4 easier, and good weapon maintenance reduced the number of misfeeds.[48]

2006 CNA report

In December 2006, the Center for Naval Analyses released a report on U.S. small arms in combat. The CNA conducted surveys on 2,608 troops returning from combat in Iraq and Afghanistan over the past 12 months. Only troops who fired their weapons at enemy targets were allowed to participate. 917 troops were armed with M4 Carbines, making up 35 percent of the survey. 89 percent of M4 users (816 troops) reported they were satisfied with the weapon. 90 percent (825 troops) were satisfied with handling qualities such as handguards, size, and weight. M4 users had the highest levels of satisfaction with weapon performance, including 94 percent (862 troops) with accuracy, 92 percent (844 troops) with range, and 93 percent (853 troops) with rate of fire. Only 19 percent of M4 users (174 troops) reported a stoppage, while 82 percent of those that experienced a stoppage said it had little impact on their ability to clear the stoppage and re-engage their target. 53 percent of the M4 users (486 troops) never experienced failures of their magazines to feed. 81 percent (743 troops) did not need their rifles repaired while in theater. 80 percent (734 troops) were confident in the M4’s reliability, defined as level of soldier confidence their weapon will fire without malfunction, and 83 percent (761 troops) were confident in its durability, defined as level of soldier confidence their weapon will not break or need repair. Both factors were attributed to high levels of soldiers performing their own maintenance. 54 percent of M4 users offered recommendations for improvements. 20 percent of requests were for greater bullet lethality, and 10 percent was better quality magazines, as well as other minor recommendations. Some M16 users expressed their desire to be issued the M4.[49] Some issues have been addressed with the issuing of the improved STANAG magazine in March 2009,[50][51] and the M855A1 Enhanced Performance Round in June 2010.[52]

2007 dust test

In the fall 2007, the Army tested the M4 against three other carbines in “sandstorm conditions” at Aberdeen Proving GroundMaryland: the Heckler & Koch XM8Fabrique Nationale de Herstal SOF Combat Assault Rifle (SCAR) and the Heckler & Koch HK416. Ten of each type of rifle were used to fire 6,000 rounds each, for a total of 60,000 rounds per rifle type.[53] The M4 suffered far more stoppages than its competitors: 882 stoppages, 19 requiring an armorer to fix. The XM8 had the fewest stoppages, 116 minor stoppages and 11 major ones, followed by the FN SCAR with 226 stoppages and the HK416 with 233.[54][55]

Despite 863 minor stoppages—termed “class one” stoppages, which require 10 seconds or less to clear, or “class two” stoppages, which require more than ten seconds to clear—the M4 functioned well, with over 98 percent of the 60,000 total rounds firing without a problem. The Army said it planned to improve the M4 with a new cold-hammer-forged barrel to give longer life and more reliable magazines to reduce the stoppages. Magazine failures caused 239 of the M4’s 882 failures. Army officials said the new magazines could be combat-ready by spring if testing went well.[56] The Army began issuing an improved STANAG magazine in March 2009.[50][51]

According to the Army, the M4 only suffered 296 stoppages, and said that the high number reported could be attributed to discrepancies in the scoring process. The Army testing command stated that, if the number of stoppages caused by a broken part met some threshold, they would be eliminated from the final report pending redesign of the part. Colt also claimed that the testing conditions were unfair to the M4, as the M4s used in the test were normal guns from active inventory, with remaining service life varying randomly. Further, the trial M4s had burst-mode fire groups, which are more complicated and prone to failure than the fully automatic fire groups the other manufacturers presented for testing.[57]

There were three extreme dust tests performed in 2007. The 2nd Summer 2007 results showed a large difference from the later fall test with the M4 having 148 class 1 stoppages due to rifle malfunctions and 148 class 1 stoppages due to magazine stoppages. The full-size M16 rifle had 61 stoppages during the same extreme dust test.[58]

Reliability

In early 2010, two journalists from the New York Times spent three months with soldiers and Marines in Afghanistan. While there, they questioned around 100 infantrymen about the reliability of their M4 Carbines, as well as the M16 rifle. Troops did not report to be suffering reliability problems with their rifles. While only 100 troops were asked, they fought at least a dozen intense engagements in Helmand Province, where the ground is covered in fine powdered sand (called “moon dust” by troops) that can stick to firearms. Weapons were often dusty, wet, and covered in mud. Intense firefights lasted hours with several magazines being expended. Only one soldier reported a jam when his M16 was covered in mud after climbing out of a canal. The weapon was cleared and resumed firing with the next chambered round. Furthermore, a Marine Chief Warrant Officer reported that there were no issues with his battalion‘s 700 M4s and 350 M16s.[59]

The reliability of the M4 has increased as the design was upgraded. In 1990, the M4 was required to fire 600 mean rounds between stoppages using M855 ammunition. In 2013, the current M4A1 version can fire 1,691 mean rounds between stoppages using M855A1 ammunition.[60]

During the 2009 Marine Corps Infantry Automatic Rifle testing, the Colt IAR displayed a MRBS of CLASS I/II Stoppages of 952 rounds, with a MRBEFF of Class III Stoppages of 60,000 rounds.[61]

Gas piston

An array of firearms accessory makers have offered gas piston conversion kits for the M4. The claimed benefits include less needed lubrication for the bolt carrier group to run reliably and reduced fouling.[62] The argument against it is increased weight and reduced accuracy.[citation needed] The Enhanced M4 uses an articulating link piston operating system.

Complicating the Army search for higher reliability in the M4 is a number of observations of M4 gas piston alternatives that suffer unintended design problems. The first is that many of the gas piston modifications for the M4 isolate the piston so that piston jams or related malfunction require the entire weapon be disassembled, such disassembly cannot be performed by the end user and requires a qualified armorer to perform out of field, whereas almost any malfunction with the direct-impingement system can be fixed by the end user in field. The second is that gas piston alternatives use an off-axis operation of the piston that can introduce carrier tilt, whereby the bolt carrier fails to enter the buffer tube at a straight angle, resulting in part wearing. This can also tilt the bolt during extraction, leading to increased bolt lug failures. The third is that the use of a sound suppressor results in hot gases entering the chamber, regardless of a direct-gas impingement or gas piston design choice. The gas piston system may also cause the firearm to become proprietary to the manufacturer, making modifications and changes with parts from other manufacturers difficult.

M4 SOPMOD II in Anime design

Assault Rifle ” AK-47 “

AK-47

AK-47[N 1]
АК-47.jpg

AK-47 Type 2A with ribbed stamped-steel magazine and 6H2 bayonet
Type Assault rifle
Place of origin Soviet Union
Service history
In service 1949–1974 (Soviet Union)
1949–present (other countries)
Used by See Users
Wars See Conflicts
Production history
Designer Mikhail Kalashnikov
Designed 1946–1948[1]
Manufacturer Kalashnikov Concern and various others including Norinco
Produced 1949–present
No. built ≈ 75 million AK-47s, 100 million Kalashnikov-familyweapons.[2][3]
Variants See Variants
Specifications
Weight Without magazine:
3.47 kg (7.7 lb)
Magazine, empty:
0.43 kg (0.95 lb) (early issue)[4]
0.33 kg (0.73 lb) (steel)[5]
0.25 kg (0.55 lb) (plastic)[6]
0.17 kg (0.37 lb) (light alloy)[5]
Length Fixed wooden stock:
880 mm (35 in)[6]
875 mm (34.4 in) folding stock extended
645 mm (25.4 in) stock folded[4]
Barrel length Overall length:
415 mm (16.3 in)[6]
Rifled bore length:
369 mm (14.5 in)[6]

Cartridge 7.62×39mm
Action Gas-operatedrotating bolt
Rate of fire Cyclic rate of fire:
600 rds/min[6]
Combat rate of fire:
Semi-auto 40 rds/min[6]
Bursts 100 rds/min[6]
Muzzle velocity 715 m/s (2,350 ft/s)[6]
Effective firing range 350 m (380 yd)[6]
Feed system 30-round detachable box magazine[6]
There are also 5- 10-, 20- and 40-round box and 75- and 100-round drum magazinesavailable
Sights 100–800 m adjustable iron sights
Sight radius:
378 mm (14.9 in)[6]

The AK-47AK, or as it is officially known (RussianАвтома́т Кала́шниковаtr. Avtomát Kaláshnikovalit. Kalashnikov’s Automatic Rifle), also known as the Kalashnikov, is a gas-operated7.62×39mm assault rifle, developed in the Soviet Union by Mikhail Kalashnikov. It is the originating firearm of the Kalashnikov rifle (or “AK”) family.

Design work on the AK-47 began in 1945. In 1946, the AK-47 was presented for official military trials, and in 1948, the fixed-stock version was introduced into active service with selected units of the Soviet Army. An early development of the design was the AKS (S—Skladnoy or “folding”), which was equipped with an underfolding metal shoulder stock. In early 1949, the AK-47 was officially accepted by the Soviet Armed Forces[7] and used by the majority of the member states of the Warsaw Pact.

Even after almost seven decades, the model and its variants remain the most popular and widely used assault rifles in the world because of their substantial reliability under harsh conditions, low production costs compared to contemporary Western weapons, availability in virtually every geographic region and ease of use. The AK-47 has been manufactured in many countries and has seen service with armed forces as well as irregular forces and insurgencies worldwide, and was the basis for developing many other types of individual, crew-served and specialised firearms. As of 2004, “Of the estimated 500 million firearms worldwide, approximately 100 million belong to the Kalashnikov family, three-quarters of which are AK-47s”.[2]

History

Origins

During World War II, the Sturmgewehr 44 assault rifle used by German forces made a deep impression on their Soviet counterparts.[8][9] The select-fire rifle was chambered for a new intermediate cartridge, the 7.92×33mm Kurz, and combined the firepower of a submachine gun with the range and accuracy of a rifle.[10][11] On 15 July 1943, an earlier model of the Sturmgewehr was demonstrated before the People’s Commissariat of Arms of the USSR.[12] The Soviets were impressed with the weapon and immediately set about developing an intermediate caliber fully automatic rifle of their own,[8][9] to replace the PPSh-41 submachine guns and outdated Mosin–Nagantbolt-action rifles that armed most of the Soviet Army.[13]

The Soviets soon developed the 7.62×39mm M43 cartridge,[12] the semi-automatic SKS carbine and the RPD light machine gun.[14] Shortly after World War II, the Soviets developed the AK-47 assault rifle, which would quickly replace the SKS in Soviet service.[15][16] Introduced in 1959, the AKM is a lighter stamped steel version and the most ubiquitous variant of the entire AK series of firearms. In the 1960s, the Soviets introduced the RPK light machine gun, an AK type weapon with a stronger receiver, a longer heavy barrel, and a bipod, that would eventually replace the RPD light machine gun.[14]

Concept

A Type 2A AK-47, the first machined receiver variation

Mikhail Kalashnikov began his career as a weapon designer in 1941, while recuperating from a shoulder wound which he received during the Battle of Bryansk.[3][17] Kalashnikov himself stated…”I was in the hospital, and a soldier in the bed beside me asked: ‘Why do our soldiers have only one rifle for two or three of our men, when the Germans have automatics?’ So I designed one. I was a soldier, and I created a machine gun for a soldier. It was called an Avtomat Kalashnikova, the automatic weapon of Kalashnikov—AK—and it carried the date of its first manufacture, 1947.”[18]

The AK-47 is best described as a hybrid of previous rifle technology innovations. “Kalashnikov decided to design an automatic rifle combining the best features of the American M1 and the German StG44.”[19] Kalashnikov’s team had access to these weapons and had no need to “reinvent the wheel”. Kalashnikov himself observed: “A lot of Russian Army soldiers ask me how one can become a constructor, and how new weaponry is designed. These are very difficult questions. Each designer seems to have his own paths, his own successes and failures. But one thing is clear: before attempting to create something new, it is vital to have a good appreciation of everything that already exists in this field. I myself have had many experiences confirming this to be so.”[17]

There are claims about Kalashnikov copying other designs, like Bulkin’s TKB-415[20] or Simonov’s AVS-31.[21]

Early designs

Kalashnikov started work on a submachine gun design in 1942[22] and with a light machine gun in 1943.[23][24] “Early in 1944, Kalashnikov was given some 7.62×39mm M43 cartridges and informed that there were several designers working on weapons for this new Soviet small-arms cartridge. It was suggested to him that this new weapon might well lead to greater things, and he undertook work on the new rifle.”[25] In 1944, he entered a design competition with this new 7.62×39mm, semi-automatic, gas-operated, long stroke piston, carbine, strongly influenced by the American M1 Garand.[26] “The rifle that Kalashnikov designed was in the same class as the familiar SKS-45 Simonov with fixed magazine and gas tube above the barrel.”[25] However, this new Kalashnikov design lost out to a Simonov design.[27]

In 1946, a new design competition was initiated to develop a new assault rifle.[28] Kalashnikov submitted an entry. It was gas-operated rifle with a short-stroke gas piston above the barrel, a breech-block mechanism similar to his 1944 carbine, and a curved 30-round magazine.[29] Kalashnikov’s rifles AK-1 (with a milled receiver) and AK-2 (with a stamped receiver) proved to be reliable weapons and were accepted to a second round of competition along with other designs.

These prototypes (also known as the AK-46) had a rotary bolt, a two-part receiver with separate trigger unit housing, dual controls (separate safety and fire selector switches) and a non-reciprocating charging handle located on the left side of the weapon.[29][30] This design had many similarities to the STG 44.[31] In late 1946, as the rifles were being tested, one of Kalashnikov’s assistants, Aleksandr Zaitsev, suggested a major redesign to improve reliability. At first, Kalashnikov was reluctant, given that their rifle had already fared better than its competitors. Eventually, however, Zaitsev managed to persuade Kalashnikov.

1955 AK-47 with a milled Type 3A receiver showing the milled lightening cut on the side above the magazine that for Type 3 receivers is slanted to the barrel axis

In November 1947, the new prototypes (AK-47s) were completed. It utilized a long-stroke gas piston above the barrel. The upper and lower receivers were combined into a single receiver. The selector and safety were combined into a single control-lever/dust-cover on the right side of the rifle. And, the bolt-handle was simply attached to the bolt-carrier. This simplified the design and production of the rifle. The first army trial series began in early 1948.[32] The new rifle proved to be reliable under a wide range of conditions with convenient handling characteristics. In 1949, it was adopted by the Soviet Army as “7.62 mm Kalashnikov assault rifle (AK)”.[7]

Further development

AKMS with a stamped Type 4B receiver (top), and an AK-47 with a milled Type 2A receiver

There were many difficulties during the initial phase of production. The first production models had stamped sheet metal receivers with a milled trunnion and butt stock insert, and a stamped body. Difficulties were encountered in welding the guide and ejector rails, causing high rejection rates.[33] Instead of halting production, a heavy[N 2] machined receiver was substituted for the sheet metal receiver. Even though production of these milled rifles started in 1951, they were officially referred to as AK-49, based on the date their development started, but they are much widely known in the collectors’ and current commercial market as “Type 2 AK-47”.[34][35] This was a more costly process, but the use of machined receivers accelerated production as tooling and labor for the earlier Mosin–Nagant rifle’s machined receiver were easily adapted.[36] Partly because of these problems, the Soviets were not able to distribute large numbers of the new rifle to soldiers until 1956. During this time, production of the interim SKS rifle continued.[33]

Once the manufacturing difficulties of non milled receivers had been overcome, a redesigned version designated the AKM (M for “modernized” or “upgraded”; in Russian: Автомат Калашникова Модернизированный [Avtomat Kalashnikova Modernizirovanniy]) was introduced in 1959.[34] This new model used a stamped sheet metal receiver and featured a slanted muzzle brake on the end of the barrel to compensate for muzzle rise under recoil. In addition, a hammer retarder was added to prevent the weapon from firing out of battery (without the bolt being fully closed), during rapid or fully automatic fire.[33] This is also sometimes referred to as a “cyclic rate reducer”, or simply “rate reducer”, as it also has the effect of reducing the number of rounds fired per minute during fully automatic fire. It was also roughly one-third lighter than the previous model.[34]

Receiver type Description[36]
Type 1A/B The original stamped receiver for the AK-47 first adopted and produced in 1949. The 1B was modified for an underfolding stock with a large hole present on each side to accommodate the hardware for the underfolding stock.
Type 2A/B The first milled receiver made from steel forging. It went into production in 1951 and production ended between 1953 and 1954. The Type 2A has a distinctive socketed metal “boot” connecting the butt stock to the receiver and the milled lightening cut on the sides runs parallel to the barrel.
Type 3A/B “Final” version of the AK milled receiver made from steel bar stock. It went into production between 1953 and 1954. The most ubiquitous example of the milled-receiver AK. The milled lightening cut on the sides is slanted to the barrel axis.
Type 4A/B AKM receiver stamped from a smooth 1.0 mm (0.04 in) sheet of steel supported extensively by pins and rivets. It went into production in 1959. Overall, the most-used design in the construction of the AK-series rifles.

Both licensed and unlicensed production of the Kalashnikov weapons abroad were almost exclusively of the AKM variant, partially due to the much easier production of the stamped receiver. This model is the most commonly encountered, having been produced in much greater quantities. All rifles based on the Kalashnikov design are frequently referred to as AK-47s in the West, although this is only correct when applied to rifles based on the original three receiver types.[37] In most former Eastern Bloc countries, the weapon is known simply as the “Kalashnikov” or “AK”. The differences between the milled and stamped receivers includes the use of rivets rather than welds on the stamped receiver, as well as the placement of a small dimple above the magazine well for stabilization of the magazine.

Replacement

In 1974, the Soviets began replacing their AK-47 and AKM rifles with a newer design, the AK-74, which uses 5.45×39mm ammunition. This new rifle and cartridge had only started to be manufactured in Eastern European nations when the Soviet Union collapsed, drastically slowing production of the AK-74 and other weapons of the former Soviet bloc.

Design

The AK-47 was designed to be a simple, reliable fully automatic rifle that could be manufactured quickly and cheaply, using mass production methods that were state of the art in the Soviet Union during the late 1940s.[38] The AK-47 uses a long stroke gas system that is generally associated with great reliability in adverse conditions.[26][39][40] The large gas piston, generous clearances between moving parts, and tapered cartridge case design allow the gun to endure large amounts of foreign matter and fouling without failing to cycle.

Cartridge

Wound Profiles of Russian small-arms ammunition compiled by Dr. Martin Fackler on behalf of the U.S. military

The AK fires the 7.62×39mm cartridge with a muzzle velocity of 715 m/s (2,350 ft/s).[6] The cartridge weight is 16.3 g (0.6 oz), the projectile weight is 7.9 g (122 gr).[41] The original Soviet M43 bullets are 123 grain boat-tail bullets with a copper-plated steel jacket, a large steel core, and some lead between the core and the jacket. The AK has excellent penetration when shooting through heavy foliage, walls or a common vehicle’s metal body and into an opponent attempting to use these things as cover. The 7.62×39mm M43 projectile does not generally fragment when striking an opponent and has an unusual tendency to remain intact even after making contact with bone. The 7.62×39mm round produces significant wounding in cases where the bullet tumbles (yaws) in tissue,[42] but produces relatively minor wounds in cases where the bullet exits before beginning to yaw.[43][44][45] In the absence of yaw, the M43 round can pencil through tissue with relatively little injury.[43][46]

Most, if not all, of the 7.62×39mm ammunition found today is of the upgraded M67 variety. This variety deleted the steel insert, shifting the center of gravity rearward, and allowing the projectile to destabilize (or yaw) at about 3.3 in (8.4 cm), nearly 6.7 in (17 cm) earlier in tissue than the M43 round.[47] This change also reduces penetration in ballistic gelatin to ~25 in (64 cm) for the newer M67 round versus ~29 in (74 cm) for the older M43 round.[47][48] However, the wounding potential of M67 is mostly limited to the small permanent wound channel the bullet itself makes, especially when the bullet yaws.[47]

Operating mechanism

The gas-operated mechanism of a Chinese AK-47

To fire, the operator inserts a loaded magazine, pulls back and releases the charging handle, and then pulls the trigger. In semi-automatic, the firearm fires only once, requiring the trigger to be released and depressed again for the next shot. In fully automatic, the rifle continues to fire automatically cycling fresh rounds into the chamber until the magazine is exhausted or pressure is released from the trigger. After ignition of the cartridge primer and propellant, rapidly expanding propellant gases are diverted into the gas cylinder above the barrel through a vent near the muzzle. The build-up of gases inside the gas cylinder drives the long-stroke piston and bolt carrier rearward and a cam guide machined into the underside of the bolt carrier, along with an ejector spur on the bolt carrier rail guide, rotates the bolt approximately 35° and unlocks it from the barrel extension via a camming pin on the bolt. The moving assembly has about 5.5 mm (0.2 in) of free travel, which creates a delay between the initial recoil impulse of the piston and the bolt unlocking sequence, allowing gas pressures to drop to a safe level before the seal between the chamber and the bolt is broken. The AK-47 does not have a gas valve; excess gases are ventilated through a series of radial ports in the gas cylinder. The Kalashnikov operating system offers no primary extraction upon bolt rotation, but uses an extractor claw to eject the spent cartridge case.[49]

Barrel

AK-47 barrel and its distinctive gas block with a horizontal row of gas relief ports

The rifle received a barrel with a chrome-lined bore and four right-hand grooves at a 240 mm (1 in 9.45 in) rifling twist rate. The gas block contains a gas channel that is installed at a slanted angle in relation to the bore axis. The muzzle is threaded for the installation of various muzzle devices such as a muzzle brake or a blank-firing adaptor.

Gas block

The gas block of the AK-47 features a cleaning rod capture or sling loop. Gas relief ports that alleviate gas pressure are placed horizontally in a row on the gas cylinder.

Fire selector

Việt Cộng soldier armed with an AK-47, standing beneath the flag of the National Liberation Front of South Vietnam

The fire selector is a large lever located on the right side of the rifle, it acts as a dust-cover and prevents the charging handle from being pulled fully to the rear when it is on safe.[50] It is operated by the shooter’s right fore-fingers and has 3 settings: safe (up), full-auto (center), and semi-auto (down).[50] The reason for this is that under stress a soldier will push the selector lever down with considerable force bypassing the full-auto stage and setting the rifle to semi-auto.[50] To set the AK-47 to full-auto requires the deliberate action of centering the selector lever.[50] To operate the fire selector lever, right handed shooters have to briefly remove their right hand from the pistol grip, which is ergonomically sub-optimal. Some AK-type rifles also have a more traditional selector lever on the left side of the receiver just above the pistol grip.[50] This lever is operated by the shooter’s right thumb and has three settings: safe (forward), full-auto (center), and semi-auto (backward).[50]

Sights

Rear sight of a Chinese Type 56, featuring 100 to 800 m (109 to 875 yd) settings and omission of a battle zero setting

The AK-47 uses a notched rear tangent iron sight calibrated in 100 m (109 yd) increments from 100 to 800 m (109 to 875 yd).[51] The front sight is a post adjustable for elevation in the field. Horizontal adjustment requires a special drift tool and is done by the armory before issue or if the need arises by an armorer after issue. The sight line elements are approximately 48.5 mm (1.9 in) over the bore axis. The “point-blank range” battle zero setting “П” standing for постояннаяon (constant) on the 7.62×39mm AK-47 rear tangent sight element corresponds to a 300 m (328 yd) zero.[51][52] These settings mirror the Mosin–Nagant and SKSrifles, which the AK-47 replaced. For the AK-47 combined with service cartridges, the 300 m battle zero setting limits the apparent “bullet rise” within approximately −5 to +31 cm (−2.0 to 12.2 in) relative to the line of sight. Soldiers are instructed to fire at any target within this range by simply placing the sights on the center of mass (the belt buckle, according to Russian and former Soviet doctrine) of the enemy target. Any errors in range estimation are tactically irrelevant, as a well-aimed shot will hit the torso of the enemy soldier. Some AK-type rifles have a front sight with a flip-up luminous dot that is calibrated at 50 m (55 yd), for improved night fighting.[51]

Furniture

The AK-47 was originally equipped with a buttstock, handguard and an upper heat guard made from solid wood. With the introduction of the Type 3 receiver the buttstock, lower handguard and upper heatguard were manufactured from birch plywood laminates.[36] Such engineered woods are stronger and resist warping better than the conventional one-piece patterns, do not require lengthy maturing, and are cheaper. The wooden furniture was finished with the Russian amber shellac finishing process.[citation needed] AKS and AKMS models featured a downward-folding metal butt-stock similar to that of the German MP40 submachine-gun, for use in the restricted space in the BMP infantry combat vehicle, as well as by paratroops. All 100 series AKs use plastic furniture with side-folding stocks.

Magazines

“Bakelite” rust-colored steel-reinforced 30-round plastic box 7.62×39mm AK magazines. Three magazines have an “arrow in triangle” Izhmash arsenal mark on the bottom right. The other magazine has a “star” Tula arsenal mark on the bottom right

The standard magazine capacity is 30 rounds. There are also 10, 20, and 40-round box magazines, as well as 75-round drum magazines.

The AK-47’s standard 30-round magazines have a pronounced curve that allows them to smoothly feed ammunition into the chamber. Their heavy steel construction combined with “feed-lips” (the surfaces at the top of the magazine that control the angle at which the cartridge enters the chamber) machined from a single steel billet makes them highly resistant to damage. These magazines are so strong that “Soldiers have been known to use their mags as hammers, and even bottle openers”.[53][54] This contributes to the AK-47 magazine being more reliable, but makes it heavier than U.S. and NATO magazines.

The early slab-sided steel AK-47 30-round detachable box magazines had 1 mm (0.039 in) sheet-metal bodies and weigh 0.43 kg (0.95 lb) empty.[40] The later steel AKM 30-round magazines had lighter sheet-metal bodies with prominent reinforcing ribs weighing 0.33 kg (0.73 lb) empty.[40][55] To further reduce weight, a light weight magazine with an aluminum body with a prominent reinforcing waffle rib pattern weighing 0.19 kg (0.42 lb) empty was developed for the AKM that proved to be too fragile and the small issued amount of these magazines were quickly withdrawn from service. As a replacement steel-reinforced 30-round plastic 7.62×39mm box magazines were introduced. These rust-colored magazines weigh 0.24 kg (0.53 lb) empty and are often mistakenly identified as being made of Bakelite (a phenolic resin), but were actually fabricated from two-parts of AG-S4 molding compound (a glass-reinforced phenol-formaldehyde binder impregnated composite), assembled using an epoxy resin adhesive.[56][57][58] Noted for their durability, these magazines did however compromise the rifle’s camouflage and lacked the small horizontal reinforcing ribs running down both sides of the magazine body near the front that were added on all later plastic magazine generations.[58] A second generation steel-reinforced dark-brown (color shades vary from maroon to plum to near black) 30-round 7.62×39mm magazine was introduced in the early 1980s, fabricated from ABS plastic. The third generation steel-reinforced 30-round 7.62×39mm magazine is similar to the second generation, but is darker colored and has a matte nonreflective surface finish. The current issue steel-reinforced matte true black nonreflective surface finished 7.62×39mm 30-round magazines, fabricated from ABS plastic weigh 0.25 kg (0.55 lb) empty.[6]

Early steel AK-47 magazines are 9.75 in (248 mm) long; the later ribbed steel AKM and newer plastic 7.62×39mm magazines are about 1 in (25 mm) shorter.[59][60]

The transition from steel to mainly plastic magazines yields a significant weight reduction and allows a soldier to carry more ammunition for the same weight.

Rifle Cartridge Cartridge weight Weight of empty magazine Weight of loaded magazine Max. 10.12 kg (22.3 lb) ammunition load*
AK-47 (1949) 7.62×39mm 16.3 g (252 gr) slab-sided steel
430 g (0.95 lb)
30-rounds
916 g (2.019 lb)[40]
11 magazines for 330 rounds
10.08 kg (22.2 lb)
AKM (1959) 7.62×39mm 16.3 g (252 gr) ribbed stamped-steel
330 g (0.73 lb)
30-rounds
819 g (1.806 lb)[40][55]
12 magazines for 360 rounds
9.83 kg (21.7 lb)
AK-103 (1994) 7.62×39mm 16.3 g (252 gr) steel-reinforced plastic
250 g (0.55 lb)
30-rounds
739 g (1.629 lb)[40][55]
13 magazines for 390 rounds
9.61 kg (21.2 lb)

All 7.62×39mm AK magazines are backwards compatible with older AK variants.

10.12 kg (22.3 lb) is the maximum amount of ammo that the average soldier can comfortably carry. It also allows for best comparison of the three most common 7.62×39mm AK magazines.

Most Yugoslavian and some East German AK magazines were made with cartridge followers that hold the bolt open when empty; however, most AK magazine followers allow the bolt to close when the magazine is empty.

Accessories

AK-47 6H2 bayonet and scabbard

AK-103 with GP-34 Grenade Launcher

AK-47 with Kalashnikov grenade launcher mounted on the muzzle

Accessories supplied with the rifle include a 387 mm (15.2 in) long 6H3 bayonet featuring a 200 mm (7.9 in) long spear point blade. The AK-47 bayonet is installed by slipping the 17.7 mm (0.70 in) diameter muzzle ring around the muzzle and latching the handle down on the bayonet lug under the front sight base.[61]

All current model AKM rifles can mount under-barrel 40 mm grenade launchers such as the GP-25and its variants, which can fire up to 20 rounds per minute and have an effective range of up to 400 metres.[62] The main grenade is the VOG-25 (VOG-25M) fragmentation grenade which has a 6 m (9 m) (20 ft (30 ft)) lethality radius. The VOG-25P/VOG-25PM (“jumping”) variant explodes 0.5–1 metre (1.6–3.3 ft) above the ground.[63]

The AK-47 can also mount a (rarely used) cup-type grenade launcher, the Kalashnikov grenade launcher that fires standard RGD-5 Soviet hand-grenades. The maximum effective range is approximately 150 meters.[64] This launcher can also be used to launch tear-gas and riot control grenades.

All current AKs (100 series) and some older models, have side rails for mounting a variety of scopes and sighting devices, such as the PSO-1 Optical Sniper Sight.[65] The side rails allow for the removal and remounting of optical accessories without interfering with the zeroing of the optic. However, the 100 series side folding stocks cannot be folded with the optics mounted.

Characteristics

Service life

The AK-47 and its variants are made in dozens of countries, with “quality ranging from finely engineered weapons to pieces of questionable workmanship.”[66] As a result, the AK-47 has a service/system life of approximately 6,000,[67] to 10,000,[68] to 15,000[69] rounds. The AK-47 was designed to be a cheap, simple, easy to manufacture assault rifle,[70] perfectly matching Soviet military doctrine that treats equipment and weapons as disposable items.[71] As units are often deployed without adequate logistical support and dependent on “battlefield cannibalization” for resupply, it is actually more cost-effective to replace rather than repair weapons.[71]

The AK-47 has small parts and springs that need to be replaced every few thousand rounds. However, “Every time it is disassembled beyond the field stripping stage, it will take some time for some parts to regain their fit, some parts may tend to shake loose and fall out when firing the weapon. Some parts of the AK-47 line are riveted together. Repairing these can be quite a hassle, since the end of the rivet has to be ground off and a new one set after the part is replaced.”[51]

Variants

7.62×39mm cartridges from Russia, China and Pakistan

Early variants (7.62×39mm)
  • Issue of 1948/49: Type 1: The very earliest models, stamped sheet metal receiver, are now very rare.
  • Issue of 1951: Type 2: Has a milled receiver. Barrel and chamber are chrome plated to resist corrosion.
  • Issue of 1954/55: Type 3: Lightened, milled receiver variant. Rifle weight is 3.47 kg (7.7 lb).[4]
  • AKS (AKS-47): Type 1, 2, or 3 receiver: Featured a downward-folding metal stock similar to that of the German MP40, for use in the restricted space in the BMP infantry combat vehicle, as well as by paratroops.
  • AKN (AKSN): Night scope rail.[72]
Modernized (7.62×39mm)
  • AKM: A simplified, lighter version of the AK-47; Type 4 receiver is made from stamped and riveted sheet metal. A slanted muzzle device was added to counter climb in automatic fire. Rifle weight is 3.1 kg (6.8 lb)[6] due to the lighter receiver. This is the most ubiquitous variant of the AK-47.
    • AKMS: Under-folding stock version of the AKM intended for airborne troops.
    • AKMN (AKMSN): Night scope rail.
    • AKML (AKMSL): Slotted flash suppressor and night scope rail.[73]
  • RPK: Hand-held machine gun version with longer barrel and bipod. The variants—RPKS, RPKN (RPKSN), RPKL (RPKSL)—mirror AKM variants. The “S” variants have a side-folding wooden stock.
AK-47 in Anime Design

Assault Rifle ” HK41″

Heckler & Koch HK416

HK416
HK416.jpg

Norwegian Army HK416N with an Aimpoint CompM4sight and a vertical foregrip
Type Assault rifle

Carbine

Squad automatic weapon (M27 IAR)

AR-15 style rifle

Place of origin Germany
Service history
In service 2004–present
Used by See Users
Production history
Manufacturer Heckler & Koch
Produced 2004–present
Variants HK416D, HK416C, HK416A5, HK416A7, M27 Infantry Automatic RifleHK417
Specifications
Weight 2.950–3.850 kg (6.50–8.49 lb)
Length 690–1,037 mm (27.2–40.8 in) (stock extended)
Barrel length HK416C: 9 in (230 mm)

HK416D: 10.5–20 in (270–510 mm)

HK416F: 11–20 in (280–510 mm)

M27 IAR: 16.5 in (420 mm)

Width 78 mm (3.1 in)
Height 236–240 mm (9.3–9.4 in)

Cartridge 5.56×45mm NATO
Action Short-stroke pistonrotating bolt
Rate of fire 700-900 rounds/min HK416A5: 850 rounds/min
Muzzle velocity 730 m/s (9 in) to 917 m/s (19.9 in)
Feed system 10, 20, 30-round detachable STANAG magazine, 100-round detachable Beta C-Mag
Sights Picatinny rail

The Heckler & Koch HK416 is an assault rifle designed and manufactured by Heckler & Koch. Although its design is in large part based on the AR-15 class of weapons, specifically the Colt M4 carbine family issued to the U.S. military, it uses an HK-proprietary short-stroke gas piston system originally derived from the ArmaLite AR-18 (the same system was also used in Heckler & Koch’s earlier G36 family of rifles). It is the standard assault rifle of the Norwegian Armed Forces, and was the weapon used by SEAL Team Six to kill Osama Bin Laden in 2011.[1][2] It has also been selected as replacement of the FAMAS in the French Armed Forces.

History

The United States Army‘s Delta Force, at the request of R&D NCO Larry Vickers, collaborated with the German arms maker Heckler & Koch to develop the new carbine in the early 1990s.[when?] During development, Heckler & Koch capitalized on experience gained developing the BundeswehrHeckler & Koch G36 assault rifle, the U.S. Army’s XM8 rifle project (cancelled in 2005) and the modernization of the British Armed Forces SA80 small arms family.[citation needed] The project was originally called the Heckler & Koch M4, but this was changed in response to a trademark infringement suit filed by Colt Defense.

Delta Force replaced its M4s with the HK416 in 2004, after tests revealed that the piston operating system significantly reduces malfunctions while increasing the life of parts.[3] The HK416 has been tested by the United States military and is in use with some law enforcement agencies. It has been adopted as the standard rifle of the Norwegian Armed Forces (2008) and the French Armed Forces (2017) and is used by many special operations units worldwide.

A modified variant underwent testing by the United States Marine Corps as the M27 Infantry Automatic Rifle. After the Marine Corps Operational Test & Evaluation Activity supervised a round of testing at MCAGCC Twentynine PalmsFort McCoy, and Camp Shelby (for dust, cold-weather, and hot-weather conditions, respectively). As of March 2012, fielding of 452 IARs has been completed of 4,748 ordered. Five infantry battalions: 1st Light Armored Reconnaissance Battalion and 2nd Battalion, 4th Marines, out of Camp Pendleton, Calif.; First Battalion, 3rd Marines, out of Marine Corps Base Hawaii; 1st Battalion, 9th Marines, out of Camp Lejeune, N.C.; and 1st Battalion, 25th Marines, out of Fort Devens, Mass. have deployed the weapon.[4][5] In December 2017, the Marine Corps revealed a decision to equip every Marine in an infantry squad with the M27.[6]

Design

A Norwegian soldier in Afghanistan, armed with the HK416N

The HK416 uses a HK-proprietary short-stroke gas piston system that derives from the HK G36, forgoing the direct impingement gas system standard in AR-15 rifles.[7][8] The HK G36 gas system was in turn partially derived from the AR-18 assault rifle designed in 1963.[9] The HK system uses a short-stroke piston driving an operating rod to force the bolt carrier to the rear. This design prevents combustion gases from entering the weapon’s interior—a shortcoming with direct impingement systems.[10] The reduction in heat and fouling of the bolt carrier group increases the reliability of the weapon and extends the interval between stoppages. During factory tests the HK416 fired 10,000 rounds in full-auto without malfunctioning.[11]

The HK416 is equipped with a proprietary accessory rail forearm with MIL-STD-1913 rails on all four sides. This lets most current accessories for M4/M16-type weapons fit the HK416. The HK416 rail forearm can be installed and removed without tools by using the bolt locking lug as the screwdriver. The rail forearm is “free-floating” and does not contact the barrel, improving accuracy.

The HK416 has an adjustable multi-position telescopic butt stock, offering six different lengths of pull. The shoulder pad can be either convex or concave and the stock features a storage space for maintenance accessories, spare electrical batteries or other small kit items. It can also be switched out for other variations like Magpul stocks.

The trigger pull is 34 N (7.6 lbf). The empty weight of a HK416 box magazine is 250 g (8.8 oz).

The HK416’s barrel is cold hammer-forged with a 20,000-round service life and features a 6 grooves 178 mm (7 in) right hand twist. The cold hammer-forging process provides a stronger barrel for greater safety in case of an obstructed bore or for extended firing sessions. Modifications for an over-the-beach (OTB) capability such as drainage holes in the bolt carrier and buffer system are available to let the HK416 fire safely after being submerged in water.

Evaluation

An Australian commando armed with an HK416 during a training exercise, 2017.

In July 2007, the U.S. Army announced a limited competition between the M4 carbineFN SCAR, HK416, XCR, and the previously-shelved HK XM8. Ten examples of each of the four competitors were involved. Each weapon fired 6,000 rounds in an extreme dust environment. The shoot-off was for assessing future needs, not to select a replacement for the M4.[12][13] The XM8 scored the best, with only 127 stoppages in 60,000 total rounds, the FN SCAR Light had 226 stoppages, while the HK416 had 233 stoppages. The M4 carbine scored “significantly worse” than the rest of the field with 882 stoppages.[3] However, magazine failures caused 239 of the M4’s 882 failures. Army officials said, in December 2007, that the new magazines could be combat-ready by spring if testing went well.[14][timeframe?]

In December 2009, a modified version of the HK416 was selected for the final testing in the Infantry Automatic Rifle program, designed to partially replace the M249 light machine gun at the squad level for the United States Marine Corps.[15] It beat the three other finalists by FN Herstal and Colt Defense. In July 2010, the HK416 IAR was designated as the M27, and 450 were procured for additional testing.[16]

The Turkish company Makina ve Kimya Endustrisi Kurumu (“Mechanical and Chemical Industry Corporation”) has considered manufacturing a copy of the HK416 as the MKEK Mehmetçik-1 for the Turkish Armed Forces.[17] Instead, the new MPT-76 rifle has been developed by KALEKALIP with MKEK as the producer, with the Mehmetçik-1 dropped from adoption into the Turkish military.[18][19]

The French armed forces conducted a rifle evaluation and trial to replace the FAMAS, and selected the HK416F as its primary firearm in 2016.[20][21]Of the 93,080 rifles, 54,575 will be a “short” version with an 280 mm (11 in) barrel weighing 3.7 kg (8.2 lb) without the ability to use a grenade launcher, and 38,505 will be a “standard” version with a 368 mm (14.5 in) barrel weighing 4 kg (8.8 lb), of which 14,915 will take FÉLIN attachments; standard rifles will be supplied with 10,767 HK269F grenade launchers. 5,000 units are supposed to be delivered in 2017, half of the order delivered by 2022, and the order fulfilled by 2028.[22] The first batch of 400 rifles was delivered on 3 May 2017.[23]

HK416A5

The HK416 was one of the weapons displayed to U.S. Army officials during an invitation-only Industry Day on November 13, 2008. The goal of the Industry Day was to review current carbine technology prior to writing formal requirements for a future replacement for the M4 carbine.[24][25] The HK416 was then an entry in the Individual Carbine competition to replace the M4. The weapon submitted was known as the HK416A5.[26] It features a stock similar to that of the G28 designated marksman rifle, except slimmer and non-adjustable. The rifle features an improved tool-less adjustable gas regulator for suppressor use, which can accommodate barrel lengths down to 267 mm (10.5 in) without modifications. It also features a redesigned lower receiver with ambidextrous fire controls, optimized magazine and ammunition compatibility, a repair kit housed inside the pistol grip, and a Flat Dark Earth color-scheme.[27] The stock has a fixed buttplate and no longer has a storage space, as well as the sling loops removed from it. The V2 HK Battle grip is incorporated, which has the V2 grip profile with the storage compartment of the V1 grip for tools. The handguard uses a new hexagonal-shaped cross bolt that cannot be removed by the bolt locking lugs, but instead by the takedown tool housed inside the grip.[28] It has a “heavy duty castle nut”, which is more robust than the previous version, therefore making that weak spot more resistant to impact. The Individual Carbine competition was cancelled before a winning weapon was chosen.[29]

Variants

A suppressed D10RS in service with Polish GROM commandos at a media demonstration in May 2011

  • HK416C: The ultra-compact variant, with “C” for Compact. The HK416C has a 228 mm (9.0 in) barrel and is expected to produce muzzle velocities of approximately 730 m/s (2,395 ft/s).[30]
  • M27 Infantry Automatic Rifle: A squad automatic weapon variant developed from the D16.5RS for the United States Marine Corps.
  • HK416A5: Improved carbine entered in the Individual Carbine competition.[27] The competition was cancelled without a weapon chosen.[29]
  • HK416A7: Variant designed for the German KSK and KSM. Most significant change is a selector which now rotates 90 degrees rather than 180 degrees as on the M16 series.[31]
  • HK417: larger caliber variant chambered for 7.62×51mm NATO

Civilian version

Civilian variants of the HK416 and HK417 introduced in 2007 were known as MR223 and MR308 (as they remain known in Europe). Both are semi-automatic rifles with several “sporterized” features. At the 2009 SHOT Show, these two firearms were introduced to the U.S. civilian market renamed respectively MR556 and MR762.[32] There is another variant of the MR556 called the MR556A1, which is an improved version of the former.[33] It was created with input from American special forces units.[34] The MR556A1 lets the upper receiver attach to any M16/M4/AR-15 family lower receiver, as the receiver take-down pins are in the same standard location. The original concept for the MR556 did not allow for this, as the take-down pins were located in a “non-standard” location. The MR223 maintains the “non-standard” location of the pins, disallowing attachment of the upper receiver to the lower receivers of any other M16/M4/AR-15 family of rifles. As of 2012, the MR556A1 upper receiver group fits standard AR-15 lower receivers without modification, and functions reliably with standard STANAG magazines. HK-USA sells a variant under the MR556A1 Competition Model nomenclature; it comes with a 14.5″ free-float Modular Rail System (MRS), 16.5″ barrel, OSS compensator and Magpul CTR buttstock. The firearm’s precision is specified as 1 MOA by Heckler & Koch. In Europe, the MR223A3 variant is sold with the same cosmetic and ergonomical improvements of the HK416A5. The French importer of Heckler & Koch in France, RUAG Defence, have announced that they are going to sell two civilian versions of the HK416F, named the MR223 F-S (14.5″ Standard version) and MR223 F-C (11″ Short version).

HK416 in Anime design

Assault Rifle ” M4A1 “

M4 carbine

Carbine, Caliber 5.56 mm, M4
PEO M4 Carbine RAS M68 CCO.jpg

Colt M4 Modular Weapon System Carbine with RAS, M68 CCO and a GPS-02 grip pod
Type Assault rifle
Carbine
Place of origin United States
Service history
In service 1994–present
Used by See Users below
Wars Colombian conflict[citation needed]
Moro conflict
Burundian Civil War[1]
Kosovo War
War in Afghanistan (2001–present)
Iraq War
Syrian Civil War[citation needed]
2013 Lahad Datu standoff[2]
Iraqi Civil War (2014–present)
Yemeni Civil War (2015-present)
Battle of Marawi[3]
Production history
Designed 1984–1993
Manufacturer See Manufacturers below
Unit cost $700 (avg. cost)[4]
Produced 1993–present
Variants M4A1
Mark 18 Mod 0 CQBR
Specifications
Weight 6.5 lb (2.9 kg) empty
7.49 lb (3.40 kg) with 30 rounds
Length 33 in (840 mm) (stockextended)
29.75 in (756 mm) (stock retracted)
Barrel length 14.5 in (370 mm)

Cartridge 5.56×45mm NATO
Caliber 5.56 mm (.223 in)
Barrels 1
Action Gas-operatedrotating bolt(Direct impingement)
Rate of fire 700–950 round/min cyclic[5]
Muzzle velocity 2,970 ft/s (910 m/s) (M855A1round)[6]
Effective firing range 500 m (550 yd)[7]
Feed system 30-round box magazine or other STANAG magazines.
Magazines with different capacities also available.
Sights Iron sights or various optics

The M4 carbine is a shorter and lighter variant of the M16A2 assault rifle. The M4 is a 5.56×45mm NATO, air-cooled, direct impingement gas-operated, magazine-fed carbine. It has a 14.5 in (370 mm) barrel and a telescoping stock.

The M4 carbine is extensively used by the United States Armed Forces and is largely replacing the M16 rifle in United States Army and United States Marine Corps combat units as the primary infantry weapon[8][9] and service rifle.

The M4 is also capable of mounting the M203 and M320 grenade launchers. The distinctive step in its barrel is for mounting the M203 with the standard hardware. The M4 is capable of firing in semi-automatic and three-round burst modes (like the M16A2 and M16A4), while the M4A1 is capable of firing in semi-automatic and fully automatic modes (like the M16A1 and M16A3).

History

Following the adoption of the M16 rifle, carbine variants were also adopted for close quarters operations. The CAR-15 family of weapons served through the Vietnam War. However, these carbines had design issues, as “the barrel length was halved” to 10 inches, which “upset the ballistics”, reducing its range and accuracy and leading “to considerable muzzle flash and blast, so that a large flash suppressor had to be fitted”.[10] “Nevertheless, as a short-range weapon it is quite adequate and thus, [despite] its caliber, [the XM177 ‘Commando’] is classed as a submachine gun.”[10] In 1984, Colt began work on a new carbine design called the XM4 combining the best features of the Colt Commando and later the M16A2 rifles.

In 1984, the first model was made, and it was tested in May 1985. The first models had an upper receiver with an A1 sight, and were given a shorter 11.5-inch barrel, but later ones were given a longer 14.5-inch barrel for the bayonet and the M203 Grenade Launcher. The second model was made in May 1986, and it was tested from May 1986 though May 1987; at the time it had an A2 Upper Sight, and it had the M16A2’s 1:7 inch rifle twist, to use the heavier 62-grain M855 rounds. The extended barrel improved the XM4’s ballistics, reduced muzzle blast and gave the XM4 the ability to mount a bayonet and the M203 grenade launcher. The XM4 was also given the cartridge deflector, as well as other minor refinements.[citation needed] In May 1991, the XM4 was renamed to the M4, and Colt made a manual.

The M4 was officially accepted into service by the U.S. military in 1994, and first saw action in the hands of U.S. troops deployed to Kosovo in 1999 in support of the NATO-led KFOR peacekeeping force. It would subsequently be used heavily by U.S. forces during the Global War on Terrorism, including Operation Enduring Freedom and Operation Iraqi Freedom. In the U.S. Army, the M4 had largely replaced M16A2s as the primary weapon of forward deployed personnel by 2005.[11] The M4 carbine also replaced most submachine guns and selected handguns in U.S. military service,[11] as it fires more effective rifle ammunition that offers superior stopping power and is better able to penetrate modern body armor.[citation needed]

A U.S. Army 82nd Airborne soldier holds an M4 carbine in VitinaKosovoin January 2000 during the NATO-led KFOR mission, the first operational use of the M4 by U.S. troops.

The United States Marine Corps has ordered its officers (up to the rank of Lieutenant Colonel) and staff non-commissioned officers to carry the M4 carbine instead of the M9 handgun.[12] This is in keeping with the Marine Corps doctrine, “Every Marine a rifleman“. The Marine Corps, however, chose the full-sized M16A4 over the M4 as its standard infantry rifle. United States Navy corpsmen E5 and below are also issued M4s instead of the M9.[13] While ordinary riflemen in the Marine Corps were armed with M16A4s, M4s were fielded by troops in positions where a full-length rifle would be too bulky, including vehicle operators and fireteam and squad leaders. As of 2013, the U.S. Marine Corps had 80,000 M4 carbines in their inventory.[14][15]

By July 2015, major Marine Corps commands were endorsing switching to the M4 over the M16A4 as the standard infantry rifle, just as the Army had done. This is because of the carbine’s lighter weight, compact length, and ability to address modern combat situations that happen mostly within close quarters; if a squad needs to engage at longer ranges, the M27 IAR can be used as a designated marksman rifle. Approval of the change would move the M16 to support personnel, while armories already had the 17,000 M4s in the inventory needed to outfit all infantrymen who needed one.[16] In October 2015, Commandant Robert Neller formally approved of making the M4 carbine the primary weapon for all infantry battalions, security forces, and supporting schools in the U.S. Marine Corps. The switch was to begin in early 2016 and be completed by September 2016.[17] In December 2017, the Marine Corps revealed a decision to equip every Marine in an infantry squad with the M27, replacing the M4 in that part of the service.[18] MARSOC will retain the M4, as its shorter barrel is more suited to how they operate in confined spaces.[19]

Improved M4

On 1 July 2009, the U.S. Army took complete ownership of the M4 design.[20] This allowed companies other than Colt to compete with their own M4 designs. The Army planned on fielding the last of its M4 requirement in 2010.[20] On 30 October 2009, Army weapons officials proposed a series of changes to the M4 to Congress. Requested changes included an electronic round counter that records the number of shots fired, a heavier barrel, and possibly replacing the direct impingement system with a gas piston system.

The benefits of this, however, have come under scrutiny from both the military and civilian firearms community.[21][22] According to a PDF detailing the M4 Carbine improvement plans released by PEO Soldier, the direct impingement system would be replaced only after reviews were done comparing the direct impingement system to commercial gas piston operating system to find out and use the best available operating system in the U.S. Army’s improved M4A1.[23]

In September 2010, the Army announced it would buy 12,000 M4A1s from Colt Firearms by the end of 2010, and would order 25,000 more M4A1s by early 2011. The service branch planned to buy 12,000 M4A1 conversion kits in early 2011. In late 2011, the Army bought 65,000 more conversion kits. From there the Army had to decide if it would upgrade all of its M4s.[24]

On 21 April 2012, the U.S. Army announced to begin purchasing over 120,000 M4A1 carbines to start reequipping front line units from the original M4 to the new M4A1 version. The first 24,000 were to be made by Remington Arms Company. Remington was to produce the M4A1s from mid-2013 to mid-2014.[25] After completion of that contract, it was to be between Colt and Remington to produce over 100,000 more M4A1s for the U.S. Army. Because of efforts from Colt to sue the Army to force them not to use Remington to produce M4s, the Army reworked the original solicitation for new M4A1s to avoid legal issues from Colt.[26] On 16 November 2012, Colt’s protest of Remington receiving the M4A1 production contract was dismissed.[27] Instead of the contract being re-awarded to Remington, the Army awarded the contract for 120,000 M4A1 carbines worth $77 million to FN Herstal on 22 February 2013.[28][29] The order is expected to be completed by 2018.[30]

Army upgrades

The M4 product improvement program (PIP) is the effort by the U.S. Army to modernize its inventory of M4 service rifles. Phase I consists of converting and replacing regular M4s with the M4A1 version. This variant of the rifle is fully automatic and has a heavier barrel, and is given ambidextrous fire controls. Phase II of the PIP explored developing a new bolt carrier. 11 designs were submitted. The competition was scheduled to conclude in summer 2013, but ended in April 2012. Over six months of testing revealed that the current bolt carrier assembly outperformed the competing designs, especially in the areas of reliability, durability, and high-temp and low-temp tests. Phase II also includes a competition for a free-floating forward rail assembly. The Army may award contracts to up to three finalists in early 2013, with the selection of a final winner in early 2014. If the Army determines that the winning rail system should be procured, delivery of new rail is anticipated by the summer of 2014.[31]

In March 2015, the Army launched a market survey to see what the small-arms industry could offer to further enhance the M4A1 to an “M4A1+” standard. Several upgrade options include an extended forward rail that will allow for a free-floated barrel for improved accuracy with a low-profile gas block that would do away with the traditional triangular fixed front sight, removable front and rear flip-up back-up iron sights, a coyote tan or “neutral color” rail for reduced visual detection, a more effective flash suppressor/muzzle brake, an improved charging handle, and a new single-stage trigger module.[32] In June 2016, the M4A1+ was canceled after reviewing the offerings and determining that there were no major upgrades currently offered.[33]

Design

M4 with M68 Close Combat Opticand AN/PAQ-4

The M4 and its variants fire 5.56×45mm NATO (and .223 Remingtonammunition, and are gas-operatedmagazine-fed, selective fire firearms with either a multi-position telescoping stock or a fixed A2 or LE tactical stock.[34]

The M4 is a shorter and lighter variant of the M16A2 rifle, with 80% parts commonality.[35] The M4 is similar to much earlier compact M16 versions, such as the 1960s-era XM177 family. Some of those visual similarities are obvious in both weapons.

The M4 with the newer, redesigned telescoping stock

As with many carbines, the M4 is handy and more convenient to carry than a full-length rifle. The price is slightly inferior ballistic performance compared to the full-size M16, with its 5.5″ (14 cm) longer barrel. This becomes most apparent at ranges of 200 yards (180 m) and beyond.

While the M4’s maneuverability makes it a candidate for non-infantry troops (vehicle crews, clerks and staff officers), it also makes it ideal for close quarters battle (CQB). The M4, along with the M16A4, have mostly replaced the M16A2 in the Army and Marines. The U.S. Air Force, for example, has transitioned completely to the M4 for Security Forces squadrons, while other armed personnel retain the M16A2. The US Navy uses M4A1s for Special Operations and vehicle crews.

Some features of the M4 and M4A1 compared to a full-length M16-series rifle include:

  • Compact size
  • Shortened barrel 14.5 in (370 mm), which includes the shorter carbine gas system.
  • Telescoping buttstock

However, there have been some criticisms of the carbine, such as lower muzzle velocities and louder report due to the shorter barrel, additional stress on parts because of the shorter gas system, and a tendency to overheat faster than the M16A2.

Accessories

An M4A1 just after firing, with an ejected case in mid-air; the M203 and M68 CCO are attached.

Like all the variants of the M16, the M4 and the M4A1 can be fitted with many accessories, such as night vision devices, suppressors, laser pointers, telescopic sights, bipods, either the M203 or M320 grenade launchers, the M26 MASS shotgun, forward hand grips, and anything else compatible with a MIL-STD-1913 Picatinny rail.

Other common accessories include the AN/PEQ-2, AN/PEQ-15 multi-mode laser, AN/PEQ-16 Advanced Combat Optical Gunsight (ACOG), and M68 CCOEOTech holographic weapon sights are part of the SOPMOD II package. Visible and IR (infrared) lights of various manufacturers are also commonly attached using various mounting methods. As with all versions of the M16, the M4 accepts a blank-firing attachment (BFA) for training purposes.

In January 2017, a USMC unit deployed with suppressors mounted to every infantry M4 service weapon. Exercises showed that having all weapons suppressed improved squad communication and surprise during engagements; disadvantages included additional heat and weight, increased maintenance, and the greater cost of equipping so many troops with the attachment.[36]

Feedramps

M4 feedramps are extended from the barrel extension into the upper receiver. This can help alleviate feeding problems that may occur as a result of the increased pressure of the shortened gas system of the M4. This problem is primarily seen in full-auto applications.

SOPMOD Block I

SOPMOD (Special Operations Peculiar Modification) Block I

U.S. Special Operations Command (USSOCOM) developed the Special Operations Peculiar Modification (SOPMOD) Block I kit for the carbines used by units under its jurisdiction. The kit features an M4A1, a Rail Interface System (RIS) handguard developed by Knight’s Armament Company, a shortened quick-detachable M203 grenade launcher and leaf sight, a KAC sound suppressor, a KAC back-up rear sight, an Insight Technologies AN/PEQ-2A visible laser/infrared designator, along with Trijicon’s ACOG TA-01NSN model and Reflex sights, and a night vision sight. This kit was designed to be configurable (modular) for various missions, and the kit is currently in service with special operations units.

SOPMOD Block II

M4A1 SOPMOD Block II in Afghanistan 2012

A second-generation SOPMOD kit (now known as SOPMOD II) includes innovative optics, such as the Elcan Specter DR, Trijicon’s ACOG TA01 ECOS model, and the Eotech 553. Block II uses the RIS II rails manufactured by Daniel Defense in both a 9.5 and 12.5 length.

Variants

Except for the very first delivery order, all U.S. military-issue M4 and M4A1 carbines possess a flat-top NATO M1913-specification (Picatinny) rail on top of the receiver for attachment of optical sights and other aiming devices — Trijicon TA01 and TA31 Advanced Combat Optical Gunsights (ACOG), EOTech 550 series holographic sights, and Aimpoint M68 Close Combat Optic (M68 CCO) being the favorite choices — and a detachable rail-mounted carrying handle. Standards are the Colt Model 920 (M4) and 921 (M4A1).

Variants of the carbine built by different manufacturers are also in service with many other foreign special forces units, such as the Australian Special Air Service Regiment (SASR). While the SASR uses weapons of essentially the same pattern built by Colt for export (Colt uses different models to separate weapons for the U.S. military and those for commercial/export purposes), the British SAS uses a variant on the basic theme, the Colt Canada (formerly DiemacoC8SFW.

M4 MWS (Modular Weapon System)

M4 MWS (Modular Weapon System) shown with various accessories including M203 grenade launcher, RIS foregrip, removable carry handle/rear sight assembly, AN/PEQ-4laser system, M68 CCO reflex sight, and the AN/PVS-4 night vision optics

Colt Model 925 carbines were tested and fitted with the Knight’s Armament Corporation (KAC) M4 RAS under the designation M4E2, but this designation appears to have been scrapped in favor of mounting this system to existing carbines without changing the designation. The U.S. Army Field Manual specifies for the Army that adding the Rail Adapter System (RAS) turns the weapon into the M4 MWS or Modular Weapon System.

M4A1

M4A1 with TA01NSN ACOG 4×32 optical sight

The M4A1 carbine is a fully automatic variant of the basic M4 carbine intended for special operations use. The M4A1 was introduced in May 1991, and was in service in 1994. The M4A1 has a “S-1-F” (safe/semi-automatic/fully automatic) trigger group, while the M4 has a “S-1-3” (safe/semi-automatic/3-round burst) trigger group. The M4A1 is used by almost all U.S special operation units including, but not limited to, Marine Force ReconArmy RangersArmy Special ForcesNavy SEALsUnited States Air Force Pararescue and Air Force Combat Control Teams. It has a maximum effective range of about 500 to 600 meters (550–660 yd).[7] The fully automatic trigger gives a more consistent trigger pull, which leads to better accuracy.[37] According to Mark A. Westrom, owner of ArmaLite, Inc., automatic fire is better for clearing rooms than burst fire.[38]

In the last few years, M4A1 carbines have been refitted or received straight from the factory with barrels with a thicker profile under the handguard. This is for a variety of reasons such as heat dissipation during full-auto, and accuracy as a byproduct of barrel weight. These heavier barrel weapons are also fitted with a heavier buffer known as the H2. Out of three sliding weights inside the buffer, the H2 possesses two tungsten weights and one steel weight, versus the standard H buffer, which uses one tungsten weight and two steel weights. These weapons, known by Colt as the Model 921HB (for Heavy Barrel), have also been designated M4A1, and as far as the government is concerned the M4A1 represents both the 921 and 921HB.

Conversion of M4s to the M4A1 began in 2014, the start of all U.S. Army forces being equipped with the automatic variant.[39] Though in service with special forces, combat in Afghanistan showed the need for providing automatic suppression fires during fire and movement for regular soldiers. The 101st Airborne Division began fielding new-built M4A1s in 2012, and the U.S. 1st Infantry Division became the first unit to convert their M4s to M4A1-standard in May 2014. Upgrades included a heavier barrel to better dissipate heat from sustained automatic firing, which also helps the rifles use the M855A1 EPR that has higher proof pressures and puts more strain on barrels. The full-auto trigger group has a more consistent trigger pull, whereas the burst group’s pull varies on where the fire control group is set, resulting in more predictable and better accuracy on semi-automatic fire. Another addition is an ambidextrous selector lever for easier use with left-handed shooters. The M4-M4A1 conversion only increases weapon weight from 7.46 lb (3.38 kg) to 7.74 lb (3.51 kg), counting a back-up iron sight, forward pistol grip, empty magazine, and sling. Each carbine upgrade costs $240 per rifle, for a total cost of $120 million for half a million conversions. 300 conversions can be done per day to equip a brigade combat team per week, with all M4A1 conversions to be completed by 2019.[40][41]

Mark 18 CQBR

An M4A1 with a Close Quarter Battle Receiver. The barrel length is 10.3 inches.

The Mk 18 Close Quarters Battle Receiver is an M4A1 with a 10.3-inch barrel upper receiver.[42] Current contractors for the Mark 18 are Colt and Lewis Machine & Tool (LMT) NSN 1005-01-527-2288.

Enhanced M4

For the Individual Carbine competition, Colt submitted their Enhanced M4 design, also known as the Colt Advanced Piston Carbine (APC). The weapon has a suppression-ready fluted barrel, which is lighter and cools better than previous M4 barrels. It is claimed to have “markedly better” accuracy. To improve reliability, Colt used an articulating link piston (ALP), which “reduces the inherent stress in the piston stroke by allowing for deflection and thermal expansion”.[43] In traditional gas piston operating systems, the force of the piston striking the bolt carrier can push the bolt carrier downwards and into the wall of the buffer tube, leading to accelerated wear and even chipped metal. This is known as carrier tilt. The ALP allows the operating rod to wiggle to correct for the downward pressure on the bolt and transfers the force straight backwards in line with the bore and buffer assembly, eliminating the carrier tilt. This relieves stress on parts and helps to increase accuracy.[44] The Individual Carbine competition was canceled before a winning weapon was chosen.[37]

Colt Commando

Though Colt has focused its attention on carbines with 14.5-inch barrels and rifles with 20-inch barrels, Colt continues to make carbines with 11.5-inch barrels, which it calls Commandos. The Colt Model 733, is their first design, and it was made in 1987. It was referred to as the M16A2 Commando, and later the M4 Commando. Unlike the XM177, the Colt Commando was a shorter variant of the M16A2. Originally, Commandos were assembled from whatever spare parts are available, so Model 733 Commandos could have A1-style upper receivers with case deflectors or A2-style upper receivers, and M16A1-profile 1:7 or M16A2-profile 1:7 barrels. Depending on the specific models, Commandos may have had three-position fire control groups (safe/semi-automatic/three-round burst), or four-position having both full-automatic and burst. The modern Model 933 has a “flattop” receiver, with a removable carrying handle and a MIL-STD-1913 Picatinny rail, with semi-automatic and automatic fire. The Model 935 Commando has the features of the Model 933, but has three-round burst fire instead of automatic. Though originally called the M16A2 Commando, Colt markets them as the M4 Commando around 1995.

Armwest LLC M4

In 2014, American firearms designer Jim Sullivan provided a video interview regarding his contributions to the M16/M4 family of rifles when working for Armalite. A noted critic of the M4, he illustrates the deficiencies found in the rifle in its current configuration. In the video, he demonstrates his “Arm West LLC modified M4”, with enhancements he believes necessary to rectify the issues with the weapon. Proprietary issues aside, the weapon is said to borrow features in his prior development, the Ultimax. Sullivan has stated (without exact details as to how) the weapon can fire from the closed bolt in semi-automatic and switch to open bolt when firing in fully automatic, improving accuracy. The weight of the cyclic components of the gun has been doubled (while retaining the weapon’s weight at less than 8 pounds). Compared to the standard M4, which in automatic fires 750-950 rounds a minute, the rate of fire of the Arm West M4 is heavily reduced both to save ammunition and reduce barrel wear. The reduced rate also renders the weapon more controllable and accurate in automatic firing.[45]

Performance

A U.S. Navy sailor fires an M4 carbine from the warship USS Vella Gulf.

The M4 carbine has been used for close quarters operations where the M16 would be too long and bulky to use effectively. It has been a compact, light, customizable, and accurate weapon. This has come at the cost of reliability and maintainability. Failure to maintain the M4 causes malfunctions. This became apparent as it saw continued use in the sandy environments of Iraq and Afghanistan.[46] Despite this, in post-combat surveys, 94 percent of soldiers rated the M4 as an effective weapons system.[47]

Early feedback

By late 2002, 89 percent of U.S. troops reported they were confident with the M4, but they had a range of problems. 34 percent of users said the handguards rattled and became excessively hot when firing, and 15 percent had trouble zeroing the M68 Close Combat Optic. 35 percent added barber brushes and 24 percent added dental picks to their cleaning kits. There were many malfunctions, including 20 percent of users experiencing a double feed, 15 percent experiencing feeding jams, and 13 percent saying that feeding problems were due to magazines. 20 percent of users were dissatisfied with weapon maintenance. Some had trouble locking the magazine into the weapon and having to chamber a round in order to lock the magazine. Soldiers also asked for a larger round to be able to kill targets with one shot. New optics and handguards made usage of the M4 easier, and good weapon maintenance reduced the number of misfeeds.[48]

2006 CNA report

In December 2006, the Center for Naval Analyses released a report on U.S. small arms in combat. The CNA conducted surveys on 2,608 troops returning from combat in Iraq and Afghanistan over the past 12 months. Only troops who fired their weapons at enemy targets were allowed to participate. 917 troops were armed with M4 Carbines, making up 35 percent of the survey. 89 percent of M4 users (816 troops) reported they were satisfied with the weapon. 90 percent (825 troops) were satisfied with handling qualities such as handguards, size, and weight. M4 users had the highest levels of satisfaction with weapon performance, including 94 percent (862 troops) with accuracy, 92 percent (844 troops) with range, and 93 percent (853 troops) with rate of fire. Only 19 percent of M4 users (174 troops) reported a stoppage, while 82 percent of those that experienced a stoppage said it had little impact on their ability to clear the stoppage and re-engage their target. 53 percent of the M4 users (486 troops) never experienced failures of their magazines to feed. 81 percent (743 troops) did not need their rifles repaired while in theater. 80 percent (734 troops) were confident in the M4’s reliability, defined as level of soldier confidence their weapon will fire without malfunction, and 83 percent (761 troops) were confident in its durability, defined as level of soldier confidence their weapon will not break or need repair. Both factors were attributed to high levels of soldiers performing their own maintenance. 54 percent of M4 users offered recommendations for improvements. 20 percent of requests were for greater bullet lethality, and 10 percent was better quality magazines, as well as other minor recommendations. Some M16 users expressed their desire to be issued the M4.[49] Some issues have been addressed with the issuing of the improved STANAG magazine in March 2009,[50][51] and the M855A1 Enhanced Performance Round in June 2010.[52]

2007 dust test

In the fall 2007, the Army tested the M4 against three other carbines in “sandstorm conditions” at Aberdeen Proving GroundMaryland: the Heckler & Koch XM8Fabrique Nationale de Herstal SOF Combat Assault Rifle (SCAR) and the Heckler & Koch HK416. Ten of each type of rifle were used to fire 6,000 rounds each, for a total of 60,000 rounds per rifle type.[53] The M4 suffered far more stoppages than its competitors: 882 stoppages, 19 requiring an armorer to fix. The XM8 had the fewest stoppages, 116 minor stoppages and 11 major ones, followed by the FN SCAR with 226 stoppages and the HK416 with 233.[54][55]

Despite 863 minor stoppages—termed “class one” stoppages, which require 10 seconds or less to clear, or “class two” stoppages, which require more than ten seconds to clear—the M4 functioned well, with over 98 percent of the 60,000 total rounds firing without a problem. The Army said it planned to improve the M4 with a new cold-hammer-forged barrel to give longer life and more reliable magazines to reduce the stoppages. Magazine failures caused 239 of the M4’s 882 failures. Army officials said the new magazines could be combat-ready by spring if testing went well.[56] The Army began issuing an improved STANAG magazine in March 2009.[50][51]

According to the Army, the M4 only suffered 296 stoppages, and said that the high number reported could be attributed to discrepancies in the scoring process. The Army testing command stated that, if the number of stoppages caused by a broken part met some threshold, they would be eliminated from the final report pending redesign of the part. Colt also claimed that the testing conditions were unfair to the M4, as the M4s used in the test were normal guns from active inventory, with remaining service life varying randomly. Further, the trial M4s had burst-mode fire groups, which are more complicated and prone to failure than the fully automatic fire groups the other manufacturers presented for testing.[57]

There were three extreme dust tests performed in 2007. The 2nd Summer 2007 results showed a large difference from the later fall test with the M4 having 148 class 1 stoppages due to rifle malfunctions and 148 class 1 stoppages due to magazine stoppages. The full-size M16 rifle had 61 stoppages during the same extreme dust test.[58]

Reliability

In early 2010, two journalists from the New York Times spent three months with soldiers and Marines in Afghanistan. While there, they questioned around 100 infantrymen about the reliability of their M4 Carbines, as well as the M16 rifle. Troops did not report to be suffering reliability problems with their rifles. While only 100 troops were asked, they fought at least a dozen intense engagements in Helmand Province, where the ground is covered in fine powdered sand (called “moon dust” by troops) that can stick to firearms. Weapons were often dusty, wet, and covered in mud. Intense firefights lasted hours with several magazines being expended. Only one soldier reported a jam when his M16 was covered in mud after climbing out of a canal. The weapon was cleared and resumed firing with the next chambered round. Furthermore, a Marine Chief Warrant Officer reported that there were no issues with his battalion‘s 700 M4s and 350 M16s.[59]

The reliability of the M4 has increased as the design was upgraded. In 1990, the M4 was required to fire 600 mean rounds between stoppages using M855 ammunition. In 2013, the current M4A1 version can fire 1,691 mean rounds between stoppages using M855A1 ammunition.[60]

During the 2009 Marine Corps Infantry Automatic Rifle testing, the Colt IAR displayed a MRBS of CLASS I/II Stoppages of 952 rounds, with a MRBEFF of Class III Stoppages of 60,000 rounds.[61]

Gas piston

An array of firearms accessory makers have offered gas piston conversion kits for the M4. The claimed benefits include less needed lubrication for the bolt carrier group to run reliably and reduced fouling.[62] The argument against it is increased weight and reduced accuracy.[citation needed] The Enhanced M4 uses an articulating link piston operating system.

Complicating the Army search for higher reliability in the M4 is a number of observations of M4 gas piston alternatives that suffer unintended design problems. The first is that many of the gas piston modifications for the M4 isolate the piston so that piston jams or related malfunction require the entire weapon be disassembled, such disassembly cannot be performed by the end user and requires a qualified armorer to perform out of field, whereas almost any malfunction with the direct-impingement system can be fixed by the end user in field. The second is that gas piston alternatives use an off-axis operation of the piston that can introduce carrier tilt, whereby the bolt carrier fails to enter the buffer tube at a straight angle, resulting in part wearing. This can also tilt the bolt during extraction, leading to increased bolt lug failures. The third is that the use of a sound suppressor results in hot gases entering the chamber, regardless of a direct-gas impingement or gas piston design choice. The gas piston system may also cause the firearm to become proprietary to the manufacturer, making modifications and changes with parts from other manufacturers difficult.

MA41 in Anime design