I also bought a 7.62x39 model as I wanted to be able to do more with it than shoot gophers and punch holes in paper, and the cheaper ammo was always a pro. I've put 600 rounds through mine without issues.
There are a couple magwell adapters available. A ploymer one and an alloy one. The alloy adapter requires permanent alteration to the receiver to work, the polymer one snaps into the receiver. There's one guy where I work that bought the polymer one and hasn't had any issues with it. I'm sure there are other's here who have done the same and chime in. I'd be interested to hear how the polymer adapter works with the XCR 7.62 pistol mags myself.