I think it is a crap shoot right out of the box on his mag's for reliability. I was told they needed to be "tuned" for 100% reliability. I spent a few extra bucks and bought one "tuned" from Derek at Millennium Customs and it is perfect. the base is a different than from Docter but that is not an issue. I picked it up at the Florida State Match so he was able to test the ones he had against my gun to make sure everything worked perfectly. Even if I had to order one I feel comfortable that it would work fine. I was able to get 21 with a little wiggle room left, I think after the spring breaks in I could get 22, even Derek thinks so.
I tried it with ammo with lengths from 1.175 to 1.200 and they all ran perfectly.