Having tried just about every mag out there, including "Colt" (Colt does not make their own mags, they have at least five suppliers, just check the mag marks), Chip McCormick, Wilson, Pachmayer, Metalform, Kimber, Springfield Armory (don't make their own, but made to their spec), Sarco "price busters", US military (real and copies), etc., etc. My go to mags are Chip McCormick. Then (in no order) Pachmayer 7 rd mags, SA, Metalform, Colt. Even the Sarco "Price Buster" mags are pretty good, especially for the price. Sure they rust at a hard look (so does Kimber guns and mags), but they WORK! For how long? I don't know, but they work quite well right out of the box and I haven't killed one yet, but haven't ridden them hard like the others. I have heard of, but not experienced, the CMC "last round drop", so I can't say what causes it or how common it is. Kimber mags are at the bottom and are generally junk in my experience. Just go to any pistolsmith site and look at they recommend and DON'T recommend, Kimber is at the bottom there too.