Sig M400 Enhanced 1 month old
At the range with the safety on and the muzzle pointed downrange, I inserted a magazine with 5 rounds of the incorrectly sized cartridges and pulled the charging handle. Moved the safety to off and fired a round downrange. Pulled the trigger again, click, no bang. Dropped the mag and checked the chamber, empty. Reinserted the mag and again pulled the charging handle and got the same results, one bang, then click, no bang.
Cleaned the gun and returned to the range the next day to shoot some 5.56 tracer rounds at surplus pumpkins (Halloween) with a coworker and his kids. First few fired as advertised, then, the same thing started again. One bang, then click no bang. So I tried some factory Remington FMJ, same thing.
I also had some extra military aluminum magazines on hand that when loaded had the same results.
1911 is Faster than 911