TuckerMojo Posted July 31, 2018 Share Posted July 31, 2018 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. Link to comment Share on other sites More sharing options...
Maximis228 Posted July 31, 2018 Share Posted July 31, 2018 By any chance is it the 180 RNFP from Xtreme? Link to comment Share on other sites More sharing options...
TuckerMojo Posted July 31, 2018 Author Share Posted July 31, 2018 Yes, for the most part, but also Rainier. Link to comment Share on other sites More sharing options...
Maximis228 Posted July 31, 2018 Share Posted July 31, 2018 (edited) I have had nothing but problems with this specific profile for some reason. IDK why. I have had everyone try my loads and they all have a roughly 10% feeding issue regardless of 1911 or 2011. I try all their ammo and it runs flawlessly in my gun. I just think that specific profile sucks for 1911s/2011s. Maybe its just us... but I hate them. And I have 10K im stuck with LOL I also only use MBX mags (Tripp Corey 10 MM for SS). Edited July 31, 2018 by Maximis228 Link to comment Share on other sites More sharing options...
Steve RA Posted July 31, 2018 Share Posted July 31, 2018 How do they work with a different bullet profile, like a RN perhaps ?? Link to comment Share on other sites More sharing options...
TuckerMojo Posted July 31, 2018 Author Share Posted July 31, 2018 I haven't tried a different profile, myself, but it is probably worth a shot. Like Maximis, I have about 10k Xtreme RNFP in inventory . I can see how a specific profile may not work in certain guns, but can't figure why the same load/length/bullets work fine in one mfr magazine but not in the other with the same gun. Link to comment Share on other sites More sharing options...
Steve RA Posted July 31, 2018 Share Posted July 31, 2018 Since you have a lot of that bullet style you might just use the brand of magazines that work with that load and gun. Link to comment Share on other sites More sharing options...
zzt Posted August 1, 2018 Share Posted August 1, 2018 The first thing I would try is narrowing the gap at the front of the feed lips. My MBX mags feed X-Treme 155 RNFP and Rainier 155 TC bullets flawlessly in both my 2011s, with OALs from 1.126" to 1.180". DO NOT try to use STI tuning specs on MBX mags. Link to comment Share on other sites More sharing options...
TuckerMojo Posted August 2, 2018 Author Share Posted August 2, 2018 What width do you recommend on the feed lips of the MBX? As I recall, STI tubes are 0.388" +/-. Link to comment Share on other sites More sharing options...
Glk21C Posted August 3, 2018 Share Posted August 3, 2018 Wide enough so the rounds don't pop out upwards past the feedlips Link to comment Share on other sites More sharing options...
Dexter Posted August 3, 2018 Share Posted August 3, 2018 I bought a mbx 155mm 9mm gave lots of problem compared to my sti gen2 magazine. Link to comment Share on other sites More sharing options...
andrewtac Posted August 3, 2018 Share Posted August 3, 2018 No issues for me mbx 40 bayou 200 rn Link to comment Share on other sites More sharing options...
EEH Posted August 3, 2018 Share Posted August 3, 2018 (edited) Biggest problem with mbx is they won’t answer e mail ! Edited August 3, 2018 by EEH Link to comment Share on other sites More sharing options...
thouston406 Posted August 6, 2018 Share Posted August 6, 2018 When I first got my MBX .40 140mm mags they would always fail to feed on the 4th round left in the magazine. I contacted Adrian (I believe) at MBX and they had me send them in and he tested fired them. He told me he couldn't recreate the problem but that he replaced the springs and followers and sent them back to me. When he sent them back I never had an issue again. Had to be something with the way the follower was seated on the spring in the mag and for some reason would nose dive the 4th round every single time on all 3 mags. Weird. Link to comment Share on other sites More sharing options...
thouston406 Posted August 6, 2018 Share Posted August 6, 2018 Their customer service was great though so I can't complain to much. Link to comment Share on other sites More sharing options...
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