U.S. Army units have reported about 3,000 M4 carbines have failed a safety inspection because of a potential glitch in the selector switch that could lead to unintended discharges, Military.com has learned.
In March 2018, the Army's Tank-automotive and Armaments Command sent out a safety-of-use message to all branches of the U.S. military, advising units to perform an updated functions check on all variants of M16s and M4s after a soldier experienced an unexplained, unintended discharge.
The Fort Knox soldier's M4A1 selector switch was stuck in-between the semi and auto detents. When the soldier pulled the trigger, the weapon failed to fire. The soldier then moved the selector switch and the weapon fired, the TACOM message states.
As of June 1, 2018, TACOM has received reports on about 50,000 weapons put through the updated functions check. Of that number, "about six percent," or 3,000 weapons, failed, R. Slade Walters, a spokesman for TACOM, told Military.com.
Task and Purpose first reported the percentage of weapons that failed the check.
TACOM officials stress it is still early in the process and about 900,000 Army weapons still must be checked, Walters said.
Military.com reached out to the Marine Corps to see what its weapons inspections have found, but did not receive a response by press time.
TACOM officials emphasize that M16 and M4 variants "will perform as intended" if personnel follow the operator's manual when using them.
"The additional functions check is to inform [TACOM] of the extent of this issue and determine the number of weapons affected," the message states.
The M4A1 is now the Army's primary individual weapon. The service is converting M4 carbines to M4A1s through the M4 Product Improvement program.
The M4A1 has been used by special operations forces for about two decades. It features a heavier barrel and a full-automatic setting instead of the three-round burst setting on standard M4s.
This article originally appeared on Military.com. Follow @military.com on Twitter.