Updated review - Sylvan Arms Sig P320 Compatible Conversion Block

Originally I couldn't get it to cycle, i felt dumb when I realized it was the JP captured recoil spring. Once I switched that for a standard flat wire spring and buffer it cycled fine. That was my fault. The reason it's still only 4 stats is that when I tried to use a Sig factory 30-round mag it wouldn't stay in the magwell. Any vibrations it just falls out like the catch isn't fully engaged. Promag 21-round mags work flawlessly so I tried an OEM 21-round mag from Sig, but they all fell out as well. The only mags that securely seat are the promags and the new ETS mags with the metal feed lips. None of the OEM SIG 320 mags will seat. Otherwise it works as advertised and seems ok. Tolerance could be a bit tighter but it mostly works. Wouldn't trust my life to it but it's fine for plinking or cost-effective experimenting with a 9mm PCC before buying something better.