I have a pre-war one that is one of my most accurate rifles. If I'm having a good day it'll shoot 1/2" at 50 yards almost every time. I got a modern scope on it using some Weaver brackets (don't ask me which ones now) that match up with the side mounts.
As for a mag, there are aftermarket mags out there, but I find it's best to just treat it as a single-shot rifle. I've never been able to get it to consistently feed well from a mag.