Most of the 1911 style .45's are interchangable, with the exception of Rugers, AND SOME LLAMA'S. I say that, because even thou the mags for LLama's look like a 1911, I've seen where each gun is different. Sometime's they work, and sometimes they don't. As far as other guns go, they are peculiar to each brand. Even thou a double stack mag might hold the same amount of rounds, the notch that is cut into the side of the mag, to lock it into a gun, will alot of times be higher or lower. If you buy an auto, best advise, take the gun with you, if your going to buy another mag, to make sure it fits!! I've even seen factory mags not lock in the gun. So try it out first. We keep trying peace, it usually doesn't work!! Remember-(12/7/41)-(9/11/01) gypsyman