I got this idea while going through my collection of holsters for guns that I no longer own. What fits what? We all know that some holsters will work quite well for guns that they weren't designed for. From my personal collection this is what I have found so far.... Just about any holster that was designed for a Glock 20/21 will fit all other Glocks. (leather AND plastic) Some might be loose, some fit perfectly. A Don Hume 715 IWB for a Glock 29/30 fits quite a few other pistols like a SW 3913 Milt Sparks 55BN made for a Sig 2340 fits a SW 908/3913 like it was made for it. Holsters designed for an Officers size 1911 will hold a PPK, Sig230/232, or similar very very well. Safariland open top mag holders for a SW59 hold single stack 45acp mags perfectly. What's in your collection that fits multiple firearms? Inquiring minds want to know.