Not really problematic. Brass kept hitting me in the forehead, and the trigger pin worked out on me in the first few hundred rounds. That was fixed by pushing back in. There was a cop on the range that day that is also a Glock armorer, and he messed with it for awhile. Couldn't find anything wrong with it. Shot a few hundred more rounds without issue. The brass to the head, well that was something I just had to deal with. No major issues, and the one was easily solved. Just 2 more issues than Ive had with the P07.