Took my pistol out the range today for the fourth time.  Once per trip I would get a FTF where the unfired round would stovepipe, or jam up in to the chamber before it could stovepipe.  Today I had it happen three times.  I just pull the slide back a bit to let the round drop out, let go of the slide and go on with emptying the mag like nothing had happened.  I thought it was just the armscor mag that came with it, but last time one of my CMC Shooting Stars did it.  Today two of my CMC Shooting Stars did it.
Any ideas on what could be causing this?  The gun functions and fires just fine except for this occasional FTF/stovepipe.  I have only been shooting Aguila 230gr FMJ because I bought so much of it on sale back when I bought the gun.  I've put a few mags worth of my Federal HST 230gr on the second range trip just to make sure she ate it and never had an issue with it.


 I have also never experienced any issue with the slide failing to lock back on an empty mag.





ETA:  It may be worth noting that after buying the gun, and before firing it, I installed a shok-buff kit.  I've done this with every 1911 I've purchased.



 

REMOVE SHOCK BUFF AND RETEST.

Check for clocking of extractor and fix as required