I picked up a new Gen4 19 last week and finally got a chance to go to the range this morning. I put 50 rounds of winchester nato 124gr fmj and another 100 rounds of winchester 115gr fmj through it without any hiccups at all. The weapon ran great just like my gen3 19. I did some one handed drills both strong hand and weak hand no problems. Reading some of these other posts made me wonder whats going on. All I can say is this one runs great.