I've got exactly 2 mags that I've actually used in my AR and are known good, as well as some new pmags, brownells branded aluminum and PSA branded aluminum mags.
How many rounds do you run through a mag before you say "yep, that one is good" and put it into the "would trust your life to it" pile?
How many rounds do you run through a mag before you say "yep, that one is good" and put it into the "would trust your life to it" pile?