Badfeeding350 - Aagil Arms Complete AR-15 .350 Legend Upper Assembly 16in Barrel Length Carbine w/ 15in M-Lok

Regarding the feed problem a couple other reviewers mentioned, I had the same issue but it wasn’t a problem with the upper receiver. It was the magazines. I ground down the curve of the magazine opening and it took care of it. The top of the shell casing was catching on the magazine. I think these “350” mags are actually 5.56.