The aftermarket thirty rounders I’ve tried are pretty iffy all around. There are some Korean made mags, both 15 and 30 round, that are supposed to be as close as you can get to USGI with out using a time machine.
Thanks for that information. I don’t think I’d heard that the Korean clips were better...I have several clips...15 and 30. The 30’s never get beyond about the 4th round. Don’t know where the clips were made..I’ve bought many and never checked that out.