i have a dozen or so from different brands: Mecgar, Chip McCormack, Shooting Star, Novak, Kimber, plus a bunch of factory mags from Colt, Taurus, Springfield Aromory, and a few milspecs. the only ones that gave me any trouble were one of the milspecs and the Novak mag. the rest function flawlessly. avoid any "novelty" mags, like the 30 round ones. those have never worked for me.