A couple of months ago, I purchased a set of MBX magazines for my .40 STI Limited pistol. They are built hell-for-stout, but have not been very reliable for me. I’ll have about one failure to feed during each match, and the failure is not limited to one or two of the magazines. The failure looks the rounds try to enter the chamber at too steep an angle and get hung up there; I suspect that the rounds are nosediving and hitting the feed ramp and then turning upward. I’ll admit I could be wrong about exactly what’s happening – I’m not stopping to inspect it closely during a stage. Bullets are 180 grain plated RNFP.
I’ve tried all of the suggestions I’ve gotten from MBX, including different recoil springs and different cartridge OAL, and have tried Grams springs and followers, with no improvement in performance. In looking closely at the seated magazine, the MBXs sit about 0.030” to 0.040” lower in the frame than my older (100% reliable) STI magazines. The Aftec extractor is in good shape, and I don’t think it’s an extractor issue since the other mags work fine.
MBX seems to have a good reputation, but I’m more than a little disappointed in these magazines and was curious if anyone else has had similar trouble with them.
