I purchased a M&P 9 maybe 5 years ago.  First time I shot it and afterwards got the Apex DAEK and installed.   Sweet!  No problems with hundreds of rounds.

Today I was doing some double taps but decided to shoot some Monarch steel 9mm vs Monarch brass or WWB.   After about 3 mags of 10 rounds each I had what I originally thought was a squib round.   I got a bunch of smoke out of the breach area and thought for sure I had just put a bullet in the barrel.  But I could not retract the slide.  I had to slightly knock the slide against the bench to get it to begin to slide rearward.   I got the round out but the bullet was still in the case however the primer had been pierced.  I had meant to bring the round back to check the powder charge but left it at the range.  Also the primer was pushed back slightly out of the case.

I continued to shoot the steel ammo but kept having light primer strikes occasionally.   Every round that failed to fire I could manually operate the slide, recock the striker and the round would fire on the 2nd attempt.  Every one of them without fail.  After about 150 rounds I switched to WWB and fired about 50 rounds more and did not have any more FTFs.   So I assume it was possible hard(er) primers on the Monarch steel cased ammo.

Thoughts?  Anyone else see issues with light primer strikes with the DAEK kit?