Great x 3...follow directions - Mean Arms 9mm Ejectored EndoMag - 3 Pack

Have used these in 3 different builds with Right To Bear and Anderson 9mm uppers, 2 different glock cut Fail Zero BCGs, and 3 different Balistic Advantage barrels with near perfect results. Yes, you must read and follow the directions. If you do, the break in takes about 5 minutes. Depending on Pmag generation, you may have to take another minute or 2 to sand the top of the Pmag lips, I had to with some of the Gen 3s.....a file is faster. Just a little off the very top of the side feed lips to allow the mag to easily lock in place. If you have any questions, issues, or mess ups contact Mean Arms. The customer service is incredibly good. I contacted to see if I could buy some back up springs....they sent me 2 free of charge and paid for shipping. Who does that! I have 8 or 9 of these broken in on the multiple systems mentioned and all mags work in all systems. Bad reviews are probably related to poor direction reading and not taking a few minutes to follow them. Thousands and thousands of rounds.......2 failures, 1 a large flat nose and 1 a JHP with a large very jagged opening.