New Maraurder & MBX Magazine Problems

[Dan O]

I just got my brand new STI Maraurder 9mm, and having issues with 2 of the MBX 140mm mags and failure to feeds. It seems that it only happens on the first 5-6 rounds when the mag is loaded with 21-22 rounds. The round catches on the upper right corner of the chamber sometimes or it feeds halfway and stays just out of battery. I am shooting factory Magtech 124 gr. Any thoughts?

[Rowdy1111]

What's the OAL? May be a little short

[v1911]

Have to broken in the mags yet? Load them to capacity and let them sit for a few days. Otherwise try different ammo and see f it's the mags or the ammo.

[Dan O]

What's the OAL? May be a little short

OAL is 1.15

Have to broken in the mags yet? Load them to capacity and let them sit for a few days. Otherwise try different ammo and see f it's the mags or the ammo.

I haven't used them much yet, approximately 500 rounds total in the last 3 days, I got everything in the mail last Friday. I just loaded them up and going to let them sit overnight and shoot them again tomorrow. Edited June 22, 2016 by Dan O

[zzt]

I use MBX mags in 40 cal. The last one I bought had the same problem as you, but only on the top two or three. I conditioned the mag by loading it fully and letting it sit until the spring had shortened enough to get the 21st round in. Then I let it sit some more. I had the same problem when I took it to the range. After the mag was empty, I compared the new mag to one of the old ones that did work. Everything looked the same except the follower on the new mag sat a lot higher in the tube; high enough to lock the slide back. I eventually looked at both mags from the top and discovered the follower in the new mag was a lot thinner than the others. They had accidentally installed a 9mm follower when they assembled the mag.

I had a new spring and lock-back follower. That worked fine, as did the spring and follower from one of the old mags. So it was definitely the follower causing the problem. Once identified, MBX took care of the problem. Check to see that you don't have a similar situation.