I have had pretty much zero problems with mine. I changed the lower for a Lingle lower, I use AK-V mags and they fit a little snug but work great.
HBI buffer, 40 degree block, shoots really nice suppressed.
I did sent the barrel to Morgan at Class 3 Machining (RIP) to have the threads fixed. Someone at Grand Power got confused and used the rifle spec for the threads, so the pitch is right but the threading is too long, so you can get issues with silencers seating properly. Morgan fixed it up to pistol threading specs.
Removing the barrel from this thing is a real SOB. There are two barrel nuts which require a special tool which ILWT sells. Mine were on there incredibly tight. I had to 3d print a vice block to hold the receiver steady and use a 1/2" impact wrench to loosen the nuts.
ILWT also sells better ejector screws, whatever they used from the factory are soft and the heads strip very easily. Replace them.