I'm on my second 9mm.
The first one I had used Colt mags and wasn't reliable.
The second one I have uses Glock Mags and is very reliable.
Only 1 FTF after the first round.
Over 500 rounds since then with zero problems.
I'm using ProMag Glock 17 compatible mags that I got on sale for 10.99 each.
It shoots under 2" groups with 115gr FMJs at 50.
8" gongs at 100 is pretty easy too - just aim at top center.
It's seems only a little louder than a 22LR.
It's now my favorite carry around on the 4wheeler gun.
My only complaint is that it doesn't hold the bolt open on last round.
Other than that, it's been a real blast.
Just get the current Glock 9mm compatible stuff from PSA and you should be GTG.
I really like introducing folks to an AR using it.
It functions/feels like an AR because it is.
When shooting, you feel like you are shooting something as it has just enough kick to feel right unlike a 22 conversion.
And yeah, it's a PSA. I bought the complete upper and a blem lower and used stuff I have laying around to complete it.
I did purchase a special 9MM buffer for it.
The buffer is heavier and includes a piece you drop in the back behind the spring to limit bolt back travel - If you don't use one of these, your bolt can travel too far back and cause problems.
The only thing I changed on the upper was the mag release lever.
I removed the plastic one provided and installed an ODIN billet bullet lever and it's much more solid and functions better.
Pardon the CLP oozing out everywhere...LOL!