apart from the hop chamber doesn't seem like the worst combo. although even with good parts things can still get messed up in the assembly.
however it might not be the assembly, misfeeding can equally be caused by mags/ammo (bad ammo can jam up and the mag spring might not be strong enough to overcome it, for midcaps at least)
the other possibility is the hop setting, you can get some weird things with the hop either fully on or fully off, so you generally want to be testing with the hop set (turn it off then on a little if it's not already dialled in for the ammo)