To be fare their 7.62x39 mags do work and I'm glad they make 'em, but: I recently ordered some mags from riflegear.com. The description claims something to the effect that they will be OEM take out mags that came out of new rifles they sold. They say they can be any brand, no choice. So I ordered the 30s first and CHA-CHING, I got all new NHMTGs, so I emmiately ordered 10 20s, I got 10 C-Products SS mags. I figured they'd be OK, C-Products has been around a while, they've had time to get their shit together. WRONG!
Had about 3 jamms per mag load, I think mostly failure to pick up the round, bolt closed on empty chamber.
1/3 of the time it locked the bolt back on last round, 1/3 time did not lock the bolt back, 1/3 of the time it locked the bolt back after the 19th round and left the 20th round floating in the upper (out of mag)
Last night I tried a different mag in a different AR and it also would fail to hold the bolt open, follower will go up in front of the bolt catch.