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New MBX Magazines that don't run out of the Box


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So I measured the feedlips and the fronts were .342-.344 (ish). The back was .346-.348(ish) these things did not run whatsoever. I went ahead and widened the front to .355 and left the back alone they seemed to work fine. 

 

Has anyone else had issues with their MBX magazines not working well from the factory? 

 

 

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14 minutes ago, jschroep said:

So I measured the feedlips and the fronts were .342-.344 (ish). The back was .346-.348(ish) these things did not run whatsoever. I went ahead and widened the front to .355 and left the back alone they seemed to work fine. 

 

Has anyone else had issues with their MBX magazines not working well from the factory? 

 

 

Mine all work fine as they came.

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Mine worked fine as they came. I have only seen issues where the gun wasn't set up right. For instance the feed ramp not cut back out of the magwell.

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Called my builder and they are gonna take care if it. Just hoping I can get one match where my magazines work lol. Last two have been mostly malfunction remedy drills... 

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I’ve run MBX since they’ve been out and have never touched the feed lips or had to squeeze them. I DO run TTI guts in them as I have had issues with stock guts.

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"Last two have been mostly malfunction remedy drills... "
That's how it was for me before I got MBX mags.

Just watch the springs. If you shoot a lot. You need new springs 2-3 times per year on your 170. Assuming you use MBX springs.
The 155s and 140s last longer.

As soon as I see any kind of malfunctions with my 170s, I replace the springs and they are back to 100%. I've seen rounds flip under the follower when the springs need replaced. That's the most common. Recently I had a couple stovepipes and a friend said it could be mag spring related. Seemed to fix it.

In a couple years of use they have never needed tuning.

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Problems with MBX just like any other mag.

I believe I'm the out layer here though based on the usual comments about MBX

I've also had very poor CS from them but again seems not the usual here.

Call MBX and have them address the concern.

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10 minutes ago, jcc7x7 said:

 

I've also had very poor CS from them but again seems not the usual here.

Call MBX and have them address the concern.

That's because we are not allowed to say anything negative towards any company on here, especially mbx. 

 

You can not call them because they do not have a phone number... Wonder why... 

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47 minutes ago, louu said:

That's because we are not allowed to say anything negative towards any company on here, especially mbx. 

 

You can not call them because they do not have a phone number... Wonder why... 

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Whats that number then?
 

If you have a problem best thing to do is email Adrian at mbxextreme@gmail.com 

Edited by Bwillis
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Adrian replied when I emailed to the issue I was having which turned out to be the Dawson heavy magwell I had put on the gun.  The magwell wasn't legal anyways so it got taken off the gun and the mags have run fine since.  Rookie error.  Sold the magwell to an open shooter.

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Posted (edited)

I sent an email and said what was going on. It's an open gun with 168-170pf ammo and a 7lb recoil spring. Gun wouldnt run the 170 mags and would hang up around the 6th to 8th shot. I switched recoil springs to a 9lb spring to try and overcome the round hitting on the ramp too low but nothing helped. Eventually I just switched to my 140's with a 9lb spring. 

 

On a side note the 9lb spring helps alot with making the dot track a little better. 

 

When I got home I took the match ammo and tried to see where it was hitting on the feed ramp. It definitely hits low on the ramp for all my mags. The fronts are much tighter than the back and I think that's making the rounds nosedive into the ramp. I'm pretty sure it's the mags.

 

I think I was probably just lucky the 140's ran given the fact that they nosedive as well.

 

Ill let y'all know what I find out from the builder and MBX

Edited by jschroep
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I imagine this is for 9mm. So, in the FAQ page, recommendation for the feed lips is .340 to .350. So, you “widened” them from in spec to out of spec. Making them narrow again is generally trickier than making them wider. You can also check the outside and inside diameter of the mags on the top and bottom compared to known mags that work well. As has already been mentioned, you need to replace the spring about once every 2-3 months depending on usage, and should be cleaning the inside of the mag with a brush and a mop every single time they hit the ground. If they aren’t working out of the box, you may consider changing the spring now because you don’t necessarily know how old the spring in those mags are. And even new springs aren’t always perfect every time. Also, check your follower for burrs and imperfections that may need a little cleanup with a hobby knife or small wire cutters.

 

Another option for people looking here with old mags is to send them back in to MBX for the mag refresh service, and get them back into spec with new guts if you don’t want to mess with them and ruin them by pounding them with a hammer yourself.
 

Ammo OAL should be OK. I run 1.160 +\- 0.005. Didn’t mention case gauge or plunk test either. Hopefully you’re doing that as well. I have about 24 mags between 3 guns, all feed lips within these specs and all guns run 100%. I know people who run and even prefer running even longer like 1.175 or 1.18. 
 

So... it may be something with your gun itself. But now the mags are out of spec, so it’s going to be tough to chase some of these things. You may consider just starting over, get new MBX mags and not mess with them, and get your gunsmith to make them run properly with mags that are in spec. That way, when you need more mags in the future, you can just open the package and they run, rather than going through this rigmarole every time.

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@CHA-LEE is very smart and knows infinitely more about this than I do. I would imagine that the OAL recommendations from MBX relate more to how the rounds behave in the mag, not necessarily how it feeds into each individual gun? Therefore, especially if this is a new gun, I think I’d rather have my rounds in MBX spec to work inside these mags and if they don’t, have the gunsmith start changing the gun? Or use different mags that can accommodate a different OAL without having problems inside the mags themselves?

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I guess if I have to bang in the feed lips to get them back in spec I will. All I know is that 2 out of the 4 magazines I got didn't work out of the box period, after I spent 500 bucks on them. I kinda don't believe the whole oh the spring in the magazine is bad because it hasn't even been used. As far as the OAL goes Limcat gave me a load and said to use 1.155 OAL. I bumped that up and am getting 1.155-1.165 OAL with the majority falling towards the middle of that range.

 

MBX is saying that it sounds like the gun is short stroking because of having  too heavy of a recoil spring on the gun. That explanation doesn't really make sense. I messed up in my initial email and told him both the 140's and 170's didn't work. It was mainly just the 170's that gave me trouble. Those didn't work with the 7lb recoil spring and bumping it up to a 9lb spring also didn't help. So I guess I'm confused about the short stroking issue. If it was short stroking wouldn't it be also having issues on the 140's with the 9lb spring? 

 

I don't see the cause and effect. It feels like I got bad 170's and good 140's. 

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I have 11 MBX mags for 9/38  and use all of them in 3 open guns.  The old ones took a lot to get running.  They were all out of spec (feed lips, too wide at top/rubbed slide, hit feedramp, etc).  The newer ones were much better.  However, I replaced all the springs and followers immediately as the mbx followers allow a round to go underneath and the springs are weak in my opinion.  Grams springs/followers and issue free for years.  

Edited by echotango
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57 minutes ago, jschroep said:

I guess if I have to bang in the feed lips to get them back in spec I will. All I know is that 2 out of the 4 magazines I got didn't work out of the box period, after I spent 500 bucks on them. I kinda don't believe the whole oh the spring in the magazine is bad because it hasn't even been used. As far as the OAL goes Limcat gave me a load and said to use 1.155 OAL. I bumped that up and am getting 1.155-1.165 OAL with the majority falling towards the middle of that range.

 

MBX is saying that it sounds like the gun is short stroking because of having  too heavy of a recoil spring on the gun. That explanation doesn't really make sense. I messed up in my initial email and told him both the 140's and 170's didn't work. It was mainly just the 170's that gave me trouble. Those didn't work with the 7lb recoil spring and bumping it up to a 9lb spring also didn't help. So I guess I'm confused about the short stroking issue. If it was short stroking wouldn't it be also having issues on the 140's with the 9lb spring? 

 

I don't see the cause and effect. It feels like I got bad 170's and good 140's. 

 

Did you read the thread I provided and do the testing suggested in there? If not, that is where you need to start.

 

I also want to point out that just because a gun builder recommends an OAL for their build that is just a starting point. Every gun/mag/ammo combo is different and usually requires a unique OAL to feed reliably. You are finding out the hard way that shooting Open isn't the same as shooting a Glock where it will feed and eat anything. If EVERYTHING in your Open config isn't setup properly then you WILL have issues. There is no easy button to figuring this stuff or a magical magazine that will fix all of your problems for you. You need to put in the work to figure out what your gun needs to function reliably. Welcome to shooting Open!!!

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Yes. It sounds like you’re going to have a lot of trouble figuring this out because it seems like you have a lot of trouble accepting advice. You took the mags out of spec for some reason. You get a load recommendation from Limcat but decide to go longer anyway. You hear advice from multiple people here but immediately dismiss it and instead continue to blame the mags (which are no longer in spec, by the way). Making them narrower and reliable also isn’t as easy as just “banging on the feed lips”. Good luck to you. Like Charlie said, this isn’t a Glock shooting factory ammo.

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1 hour ago, CHA-LEE said:

 

Did you read the thread I provided and do the testing suggested in there? If not, that is where you need to start.

 

I also want to point out that just because a gun builder recommends an OAL for their build that is just a starting point. Every gun/mag/ammo combo is different and usually requires a unique OAL to feed reliably. You are finding out the hard way that shooting Open isn't the same as shooting a Glock where it will feed and eat anything. If EVERYTHING in your Open config isn't setup properly then you WILL have issues. There is no easy button to figuring this stuff or a magical magazine that will fix all of your problems for you. You need to put in the work to figure out what your gun needs to function reliably. Welcome to shooting Open!!!

 

I read your post. When developing the loads I did the plunk test and found the Max I could load them was right at 1.168. I backed off on the OAL a bit to account for any variances in OAL and went with that. The gun and mags are on their way to Johnny. That's where I am getting the 1.155-1.165. with the majority being closer in the middle

 

Do you have any ideas as to why 140's would work and 170's wouldn't? Especially given that the feedlips width was similar across the 170's and 140's from the start?

 

Sorry if I made it sound like I ignored your advice.

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The quantity of rounds stacked up inside the magazine changes how much upward spring pressure there is. A big stick will have a higher level of upward spring pressure. If the brass has an hour glass shape due to being excessively undersized during reloading, that is going to promote nose diving (Which you are experiencing). Straight sidewall brass will always feed more reliably than undersized brass which has a dip in the side wall. The best way to test if the problem is due to the side wall straightness of the case is to buy factory ammo and see how that ammo cycles. Factory ammo will have a straight sidewall and that minimizes the chance of the rims catching on the brass leading to nose dives.

 

If you can't understand what is going on or figure it out yourself then get it to someone who can. From what you have posted so far it doesn't sound like you are using a logical troubleshooting process by eliminating one variable at a time. It sounds like you keep throwing random "fixes" at it while hoping that it will resolve the issue. As you are finding that unorganized process isn't very effective.

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Posted (edited)

My OAL is set a little shorter than the max that my gun will chamber and pass the plunk test. I could increase the OAL by a couple thou if you think that would help.  My understanding of what is going wrong in my gun came from YouTube videos on 2011 mag tuning from a reputable open gun builder. His information also lined up with what was presented in Dawson Precision's 2011 mag tuning guide. Is that approach not valid for MBX magazines? I am new to Open Guns and have two conflicting directions for tuning mags in the future. So forgive me if I seem completely confused. 

 

Are the spring coefficient's the same between 140 and 170 magazines? I understand the whole force is a function of distance compressed thing believe me. I figured you would want the same force from a fully loaded 140 as a fully loaded 170. 

 

 

Edited by jschroep
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