Mike, I run a 22 Nosler in a MPA for a practice rifle. The best running mags that I have found are the MDT 223 polymer mags with the feed lips filed out a bit to get the round up a bit higher. This allows the bolt to pick up the rebated case head. I also run the MK machining extenders for these mags to fit 10+ rounds in the mag. Without the extensions you'll only get 8. I ran into binding problems with the 308 mags when they get dirty. One workaround could be using some .100 teflon tape on the interior of the magazine to squeeze the rounds to prevent binding. I tried that briefly before I went to the MDT mags. Hope this helps.