Accidental Discharges Force US Army to Change Immediate Action Drills and M4 Selector Lever

    FN M4

    US Army's M4A1 (FN)

    A potentially fatal flaw with some of the US Army’s M4A1’s has recently emerged. Unofficial footage, filmed by troops, surfaced showing a serious malfunction where an M4A1 carbine unintentionally discharged as its selector was shifted from semi to full auto. At least 900 carbines are known to be affected by the flaw.

    The first problems were discovered by troops at Fort Knox, Kentucky in March with one solider finding that his carbine discharged as he rotated the selector fully into the detent full auto position. Since that incident a similar problem has been noted with weapons made by another manufacturer, with the weapon firing as the selector was pushed from safe to semi. This means both Colt and FN production guns have been impacted.

    The Army’s Tank and Automotive Command (TACOM), which is responsible for small arms maintenance, issued two separate safety directives in March and April – the second of these noted that the malfunction “is now believed to go beyond just the M4A1 PIP [product improvement program] weapons.” This means other rifles including M4s and M16A2, A3 and A4s may also suffer from the defect. The second safety message stated that 881 M4A1s had been tested and had exhibited the malfunction.

    M4A1 at the zero range

    Sgt. Savannah Matelski, Company D, 781st Military Intelligence (MI) Battalion (Cyber), 780th MI Brigade (Cyber), fires her M4A1 carbine rifle at the zero range on day two of the North Region Intelligence & Security Command Best Warrior Competition, May 8. (Steven Stover/US ARMY)

    No injuries as a result of the defect have been reported but the Army has devised a new in-depth function check and moved to make changes to its prescribed weapons handling techniques. This includes SPORTS, the US Army’s immediate action drill, which has not become C-SPORTS with the edition of a new first step, highlighted below:

    1. Confirm that the selector is set to semi, auto or burst.

    2. Slap upward on the magazine to make sure it is properly seated.

    3. Pull the charging handle completely to the rear and hold.

    4. Observe for ejection of case or cartridge, and ensure the cartridge or case is ejected and the chamber is clear.

    5. Release the charging handle to feed a new round.

    6. Tap the forward assist to ensure the bolt is closed.

    7. Squeeze the trigger; the weapon should fire.

    The M16 family of small arms have been in US service for over 50 years and this is the first reported incidence of this defect. The cause of the problem is being investigated by ARDEC and PEO Soldier to identify potential fixes outside the introduction of C-SPORTS. One potential explanation might be that the new ambidextrous safety/selector levers used in the Army’s M4A1 Product Improvement Program package might be out of spec.

    To address this the Army has reportedly made a change to the M4A1’s ambidextrous selector’s technical date package which will force the lever to snap into a fixed detent position rather than potentially floating between the safe, semi, full detent positions. It remains to be see if other branches have encountered similar issues. Regardless it looks likely that unit level armourers are set to be busy for the foreseeable future.

    Sources: 1 2 3

    Matthew Moss

    Matthew Moss – Assistant Editor.

    Matt is a British historian specialising in small arms development and military history. He has written for a variety of publications in both the US and UK he also runs www.historicalfirearms.info, a blog that explores the history, development and use of firearms. Matt is also co-founder of www.armourersbench.com, a new video series on historically significant small arms.

    Reach Matt at: [email protected]


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