I doubt it is the ammo or the magazines.
Since the empty case is ahead of the cartridge coming from the magazine, I suspect extractor problems. If it were the ejector, the round rising from the magazine would come up under the fired case but wouldn't try to push it back in the chamber. If it were a short cycle, I would not expect the slide to come back far enough to try to pick up the round from the magazine.
The extractor may be chipped or broken. But it may not be the extractor itself. Dirt can work under the extractor and prevent it from engaging, the extractor spring can become weak or the plunger can become dirty or rust in its hole.
[This message has been edited by Jim Keenan (edited July 01, 1999).]