American Gunsmith

The Department of Defense reported finding a small number of M16/M4 weapons that potentially could have an unintended discharge while manipulating the selector. TACOM (U.S. Army Tank-automotive & Armaments Command, a major subordinate command of Army Materiel Command) issued a Safety Of Use Message (SOUM #18-004) alerted the field of an unintended discharge on an M4A1 that had been through the Product Improvement Program, occurring after the operator pulled the trigger with the selector switch between the SEMI and AUTO detents (outside of detent). The weapon did not fire when the operator pulled the trigger and instead fired when the selector was moved further. The problem has been thought to be due to a “stack up” of differing tolerances from new parts added in the DOD’s product improvement program. It can also occur with civilian AR-15 firearms. As a result of this incident, an on-going investigation determined that there is the potential for all carbines and rifles noted above to behave in this way.

This potential mechanical problem is uncommon. The Army has converted 259,000 M4s to M4A1s in the past three years with the M4 carbine product improvement program and 881 have been found to exhibit this problem.

TACOM released an updated Function Check (SOUM #18-005) that easily determines if a M16/M4 (or AR-15) exhibits this problem. Begin by ensuring the weapon is clear by observing the chamber, the bolt face, and magazine well. The weapon should always be pointed in a safe direction. Do NOT perform this check with live ammunition. Perform a standard Function Check: Pull the trigger while on Safe (nothing should happen), rotate to Semi and pull the trigger (hammer should fall), hold the trigger down while racking the charging handle (hammer remains cocked) and then release and pull the trigger (hammer should fall.) For military weapons, rotate to Auto or Burst and check the full auto or three-round burst as usual.

If that passes as normal, continue by moving the selector lever to the Semi position then move the selector to a position between Semi and Auto (Burst for non M4A1’s) and squeeze the trigger. For non-full auto firearms, move the selector between settings. The hammer should drop when trigger is pulled and the selector is off Safe. If the hammer drops, repeat by re-cocking the hammer and slightly repositioning selector between settings again. Again, the hammer should drop when the trigger is pulled and the selector is off Safe. If hammer does not drop, move the selector in either direction. If the hammer drops without squeezing the trigger, this is a failure.

Do NOT use SPORTS or C-SPORTS

These additional steps updating the normal Function Check will readily determine if a particular M16/M4 or other AR-15 firearm is affected. If the Function Check to inspect for this problem is passed, there is absolutely no need to change Immediate Action procedures. The previous Department of Army Immediate Action procedure (“SPORTS”) has been since replaced in 2016 with an improved procedure described in Training Circular 3-22.9, which is a very good training manual, can be distributed without restriction, and is available for free download. References still using SPORTS or other variations are out of date.

First problem, an Immediate Action amendment is completely unnecessary if the Function Check is passed. Confirming correct mechanical function is an administrative action not something to do while engaging targets.

Second problem, SPORTS was replaced as an overly-convoluted and less effective approach than what the new Immediate Action procedure in TC 3-22.9 directs. Taking a tangled “immediate” six-step procedure and adding yet-another step defies the entire point of immediate action.

Third problem, this low percentage mechanical problem only occurs while manipulating the selector. Immediate Action is only necessary after attempting to engage target(s), meaning the weapon was already set to discharge (obviously) and there is no need to manipulate the selector while performing it.

TC 3-22.9, page 8-10

RULES FOR CORRECTING A MALFUNCTION
Do not attempt to place the weapon on SAFE (unless otherwise noted). Most stoppages will not allow the weapon to be placed on safe because the sear has been released or the weapon is out of battery. Attempting to place the weapon on SAFE will waste time and potentially damage the weapon.

Read more in the January 2019 issue.

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