The Army's weapons to date have suffered a 6 percent failure rate out of 52,000 inspected weapons.
The Army sent out safety-of-use messages in March and April, advising all services to perform a new functions check on M16s and M4s after a soldier's weapon fired when the selector switch became stuck between the semi and auto settings.
Officials with the Army's Tank-automotive and Armaments Command said they have received reports that approximately 52,000 weapons have been tested so far. Of those, about 3,155 failed to pass the updated functions check, Slade Walters, a spokesman for TACOM, said June 14.
But the Marine Corps' weapons have fared better.
"The Marine Corps has not received any reports of weapons that have failed the new functions check outlined in the messages," Barbara Hamby, a spokeswoman for Marine Corps Systems Command, told Military.com.
The Marine Corps has not responded to a request to provide the numbers of weapon it has inspected.
TACOM provided a breakdown of the M4s and M16s that have been inspected as of June 1.
Of the Army weapons checked thus far, most failures occurred in M4A1s. The M4A1s that had been converted from M4s suffered 2,070 failures out of 23,000 inspected -- a 9 percent failure rate.
About 16,000 original M4A1s have been inspected, with failures occurring in 960 of those weapons -- a 6 percent failure rate.
The M4A1 has been in use by special operations forces for about two decades. It features a full-automatic setting instead of the three-round burst setting on the M4, as well as a heavier barrel. The Army is in the process of converting all of its M4s to M4A1s through the M4 Product Improvement Program.
The results also showed that less than one percent of the 4,000 M4s checked failed the updated functions check. And less than one percent of the 8,500 M16A2s checked failed the test.
About 500 M16A4s were also checked, but no failures were reported.
The problem started in late March when a Fort Knox soldier's M4A1 selector switch became stuck 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.
TACOM officials stress that it is early in the process, and about Army 900,000 weapons still must be checked.
-- Matthew Cox can be reached at firstname.lastname@example.org.