With some of the cuts through .050 walls, alignment problems are hard to straighten out.
A few random comments. Protect the threads in the receiver which hold the handgrip. A 15mm x 1 tap will straighten them out if needed.The barrel has to be pressed in place. My barrel took some lathe work. Machining on the inside of the receiver may not duplicate the original (some of the cuts baffled me) and alternate methods of holding the trigger pin in place may be needed. I used neoprene washers first then hitch pins. The mag housing has a cut through it and must be dead on to feed. A 1/8” bolt will hold the two pieces of the body together temporarily.