In a moment of stupid I paid a lot of money for a 27 round KMI magazine for my Glock 21. At the range this morning EVERY time I pulled the trigger the mag dropped into the snow. I have read that some when dropped on a harder surface will pop open and sproing the ammo all over. I guess some of the 9mm mags function ok. I would stay away from the .45 mags. I should have saved my money and purchaced some good imported beer for the nascar race tomorrow night.