Both the Army and Marine Corps are checking their M4 carbines and M16 rifles for a malfunction with the selector switch that causes the weapons to fire without soldiers or Marines pulling the trigger.

TACOM has found the malfunction in 6 percent of 52,000 weapons tested so far, Walters said. The Army will test a total of 903,000 rifles and carbines over the next 6 months and it expects repairs will ...