Before you buy, check to see what followers are in the mags. I know the original USGI mags have a problem with the followers jamming in the mag. There have been several iterations on the followers and the mags that I've got have the green follower, which I believe are a generation behind. Mags with the orange followers are supposedly the latest revision, although I haven't been able to find any as of yet.
Kinda off topic, but do you use any mag pouches/carriers when shooting and if so, what kind? I'm looking for belt mounted pouches/carriers (versus a vest style) and not sure what to get.