I really don’t count trigger problems, since the 9mm carbines are so hard on triggers. Most MPX reliability issues surround the gas system, although there are also breakages of small parts. Apparently the Gen 3 gas system is better. On Gen 1 and 2 MPX carbines, some serious PCC competitors clean the gas system every night of a major match. That necessitates removing the barrel. Apparently this is not an issue with the MCX, as rifle powder is much cleaner than pistol powder. Every MPX USPSA shooter I know, including myself, has had MPXs back to Sig for repair, had broken parts, and some function issues.
Likes pretty much everything in every caliber.
Most guys run their MPXs stock except for a trigger, magazine extensions and maybe a charging handle.
Likes pretty much everything in every caliber.
The flip side, is for those that want to run regular factory ammo, the MPX is way softer shooting than a blowback design. I have heard Federal makes a 130 grain Syntech load, though, for blow backs, but that is a specialized load.
I think the latest Gen 3 MPXs, like their competition model, give you the best crack at reliability.
Likes pretty much everything in every caliber.