Quote Originally Posted by Bret View Post
+1 to all this. I bought a load of them when they were available for $10 each. I still have plenty that are NIW, but all that I've tried have been 100% in my Colt 9mm SBR and my RRA 9mm SBR. Oddly, I have one plastic Promag and it's been 100% too. BTW, the RRA 9mm SBR was unreliable with the C-Products magazines, but has been 100% with the Metalforms.
I think that may be because if your RRA 9mm was like mine, it has no feed cone, just a chamber that completely supports the round. Great for hot loads as it’s got maximum case support, but if there’s any issue with the feed angle, it’s a malfunction. So having a good mag feeding at the correct angle is important. Usually feed cones are more important with Glock builds since they can’t feed as low as Colt pattern mags. Personally, I like max case support in case of an OOB and tend to save the NATO and +p loads for my AR9s.