Have had good luck with federal, if you can find them, and very good luck with precision mag out of kalifornia LA area, just check follower with thumb and make sure it is smooth at top, a buddy and I have tested at least 20, 30 round mags of precision and they all worked. Had bad luck with usa, had a machine shop weld more material on back lock to pull mag into gun higher and 20 rounds will work out of this 30 (beter than none as was before) too much money to mess with machine shop. At last (no pun intended) great western I only saw 4 precision mags, so good luck in your search.