FYI there are two types of AR9 bolts, ramped and non-ramped. Ramped allows use of a standard AR hammer, non ramped requires a 9mm hammer. I would check that out first and make sure you have the right parts. I think PSA uses hybrid stuff, whatever that means.
I built 8" pistol using NFA and spinta stuff for my wife, it's a really fun little gun. I call it the little ammo burner
