Just got back from the range with my buddy who ordered 5 of these magazines before the Newtown event.
We each put 30 rounds through each magazine for a total of 60 rounds per mag. They worked like a champ. I tried everything I know to make the mags malfunction, and nothing worked.
Considering that Mako is not price gouging, if you are looking for some AR mags, these may be worth a shot. I am thinking about ordering a few for myself.