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. Conversion of M4s to the M4A1 began in , the start of all U. Army forces being equipped with the automatic variant. Upgrades included a heavier barrel to better dissipate heat from sustained automatic firing, which also helps the rifles use the MA1 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. Three conversions can be done per day to equip a brigade combat team per week, with all M4A1 conversions to be completed by 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".
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. The modern Model has a "flattop" receiver, with a removable carrying handle and a MIL-STD Picatinny rail, with semi-automatic and automatic fire. The Model Commando has the features of the Model , but has three-round burst fire instead of automatic.
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 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.
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. By late , 89 percent of U.
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. 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.
The CNA conducted surveys on 2, 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. M4 users had the highest levels of satisfaction with weapon performance, including 94 percent troops with accuracy, 92 percent troops with range, and 93 percent troops with rate of fire. Only 19 percent of M4 users troops reported a stoppage, and 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.
Both factors were attributed to high levels of soldiers performing their own maintenance. Some M16 users expressed their desire to be issued the M4. Ten of each type of rifle were used to fire 6, rounds each, for a total of 60, rounds per rifle type.
Despite 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, 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 of the M4's failures. Army officials said the new magazines could be combat-ready by spring if testing went well. According to the Army, the M4 only suffered 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.
There were three extreme dust tests performed in The 2nd Summer results showed a large difference from the later fall test with the M4 having class 1 stoppages due to rifle malfunctions and class 1 stoppages due to magazine stoppages. The full-size M16 rifle had 61 stoppages during the same extreme dust test. In early , two journalists from the New York Times spent three months with soldiers and Marines in Afghanistan. While there, they questioned around 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 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 M4s and M16s.
The reliability of the M4 has increased as the design was upgraded. In , the M4 was required to fire mean rounds between stoppages using M ammunition. In , the current M4A1 version can fire 1, mean rounds between stoppages using MA1 ammunition.
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. 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. This article does not contain any citations or references. Please improve this article by adding a reference. For information about how to add references, see Template:Citation. The M4 was developed and produced for the United States government by Colt Firearms , which had an exclusive contract to produce the M4 family of weapons through Colt previously held a U.
The Bushmaster M4 Type Carbine is a popular example. Colt had maintained that it retains sole rights to the M4 name and design. Other manufacturers had long maintained that Colt had been overstating its rights, and that "M4" had now become a generic term for a shortened AR However, on December 8, , a District Court judge in Maine granted a summary judgment in favor of Bushmaster Firearms, dismissing all of Colt's claims except for false advertising.
On the latter claim, Colt could not recover monetary damages. The court also ruled that "M4" was now a generic name, and that Colt's trademark should be revoked. No private citizen can own an M4 in a select-fire or fully automatic configuration, as this model of fully automatic rifle was developed after the ban on fully automatic weapons available to be purchased by US citizens under the Firearms Owners' Protection Act of While many machine guns can be legally owned with a proper tax stamp from the Bureau of Alcohol, Tobacco, Firearms and Explosives, an amendment to the Firearm Owners Protection Act of barred the transfer to private citizens of machine guns made or registered in the U.
The only exception was for Special Occupational Taxpayers SOT , who are licensed machine gun dealers with demonstration letters, manufacturers, and those dealing in exports and imports. As such, only the earliest Colt M4 prototypes built prior to would be legal to own by non-SOT civilians. The Civilian replicas of the M4 typically have 16 inch barrels or standard Civilian-legal M4s are also popular with police as a patrol carbine. Military Wiki Explore. And Textron uses a new cased-telescope ammunition design that shortens and lightens the overall length of the cartridge.
The companies chosen to build optics for the rifles are experienced military vendors. Low-power variable optics from Vortex Optics, typically a power scope , have recently popped up on the weapons of U. Army and U. Both optics will include advanced fire control systems improving the likelihood of first round hits—especially during the stress of combat. The M4 carbine is a fully modernized, more compact version of the original M16 rifle first fielded in The M squad automatic weapon was originally fielded in the late s to provide high volume firepower for suppressive fire.
Type keyword s to search. Today's Top Stories. Army plans to start purchasing the Next Generation Squad Weapon in The guns will only go to frontline troops that could see combat if deployed. The Army wants new weapons that improve upon the existing M4 carbine and M squad automatic weapon. Candidates for the Next Generation Squad Weapon and associated optics. An Important Primer.
Phase two also calls for a forward rail assembly competition. The US Army is expected to place contracts with up to three finalists in The final winner is expected to be short-listed in early The deliveries of new rails are to be made by the summer of depending on the decision of the US Army. The M4 Carbine accepts 30 round magazines carrying 5. Each fully loaded round magazine weighs about 0.
The M4 Carbine is equipped with target style rear mounted sight with dual apertures. The sight can be adjusted for wind exposure and elevation. The weapon can also be fitted with advanced combat optical gunsight ACOG , reflex sights, EOTech holographic weapon sights and a night vision sight.
The M4 is a selective fire weapon offering semi-automatic and three-round burst fire modes. The M4A1 can fire rounds in fully automatic mode. The M4 can fire at the rate of to rounds per minute for an effective range of m. AKM is the main service rifle in use in the Russian Army.
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