I have had excellent results with a Metalform "Detonics" mag, and I actually use it in preference to the factory mag, as that one's upward movement is limited not by the mag catch or the base plate contacting the bottom of the frame, but by the top of the mag contacting the ejector. I was having problems with the ejector coming loose, and traced it to the mag bouncing around under recoil, and whacking the ejector with each shot. The Metalform bottoms against the frame, and it works, so that's the one I use. I've also had no trouble with a cheapy mag that I got from Gunparts, but it is UGLY, and I use it only for practice. My reloads are full-length, 7-round Metalforms, with G.I. followers, with home-made stops attached to the front, so they won't batter the ejector.
Now, on to Ted's specific problem: does your mag have tapered, G.I.-style feed lips, or short, parallel feed lips? If it's the former, try a "modern" mag with the shorter lips. They were developed to feed wadcutters, but I find they work well with all bullet shapes, and it might solve your problem. Does the gun ever jam like that when you are loading the gun, or only when the gun is cycling during live fire? If it jams when you are loading, then it's not a dynamic problem associated with grip, but is almost certainly a dimensional or other poblem with the gun or mags.