Problems with .38 super in MBX mags

[CJDOUBLETAP]

Has anyone else had problems with the new style MBX tubes using .38 super? The top center of the mag tube isn't crimped in like the older tubes. It allows the rimmed .38 super cases to pivot side to side on the rim of the case, because the rest of the case is unsupported by the feed lips.

 

I believe these mags would work with 9mm since the length of the rimless case would be contacting the feed lips.

 

The old style tube is on the right with the crimped in sides. It works with zero issues. The new design isn't pinched in at the top, allowing the round to point off to the side, since the rim of the case is the only thing touching the feed lips.

 

[Shmella]

Happens with 9mm too. Every other round is at a slight angle. Hasnt presented to be a problem as far as I can tell so far. Im using two 170s and one 140 all of them do that.

[Steelix]

It stacks fine with 38sc. I did notice that when I put 38super rounds in the mags. I was trying to use some of my old 38super rounds in my new gun, it feed ok though. 

Edited June 16, 2017 by Steelix

[CJDOUBLETAP]

22 minutes ago, Steelix said:

It stacks fine with 38sc. I did notice that when I put 38super rounds in the mags. I was trying to use some of my old 38super rounds in my new gun, it feed ok though. 

 

What length are your rounds loaded to?

 

I'm having trouble with 5 different mags all doing the same thing. About once every 25 rounds a round will get jammed up on the side of my feed ramp. I couldn't get a good picture with the c'more in the way, but the tip of the bullet is stuck between the sharp edge on the feed ramp and the frame. I've ran about 1500 rounds through the gun with STI mags with no issues.

 

Any ideas? Thanks!

 

 

[jcc7x7]

It's a good idea, and I normally do it when I build one, to bevel the bottom of the ramp so there isn't a sharp edge. You might try that and see if it solves the problem and it shouldn't cause any etc!

[CJDOUBLETAP]

23 minutes ago, jcc7x7 said:

It's a good idea, and I normally do it when I build one, to bevel the bottom of the ramp so there isn't a sharp edge. You might try that and see if it solves the problem and it shouldn't cause any etc!

Thanks man!

[magpulled]

What are he feed lip dimensions ? I've got a couple mbx that I've never used so I'm not that familiar with them. 

[Steelix]

6 hours ago, CJDOUBLETAP said:

 

What length are your rounds loaded to?

 

I'm having trouble with 5 different mags all doing the same thing. About once every 25 rounds a round will get jammed up on the side of my feed ramp. I couldn't get a good picture with the c'more in the way, but the tip of the bullet is stuck between the sharp edge on the feed ramp and the frame. I've ran about 1500 rounds through the gun with STI mags with no issues.

 

Any ideas? Thanks!

 

 

 

PD 124gr FMJ are loaded to 1.260 Oal and PD  124gr JHP are loaded to 1.235 Oal  I hope that helps. 

[bigbob21]

Brand new to open and shooting 9mm, so take with a grain of salt...

Got a new gun and bought 3 mbx mags... all 3 didn't fit the Dawson video specs, all 3 jammed a lot, nose stuck on ramp...

I tuned them all (lips and mag widths) worked on the springs to try and break them in, loaded long, down loaded from max capacity etc etc... it got better but still had more than 1 jam per mag...

Ended up switching away from precision delta and now testing out montana's cmj & jhp and Everglades 124s... all 3 feed perfect.
I kinda think the combo of my particular gun and mbx mags doesn't like precision delta bullets
Sucks too... they're priced awesome



Sent from my iPhone using Tapatalk

[Ace38super]

Before you start bending feed lips or messing with a gun you know runs with other mags, try to use a Grams spring and follower for STI/ SV. If you have a 170 tube get a 13 coil 38 super spring/follower set up. The rounds are not stacking correctly in your picture. I would use a 1.250 OAL for a round nose and 1.235 to 1.240 for a JHP. I had to ditch the MBX spring/follower to get mine to work. They are for Caspian but the principle is the same. They have been flawless with the Grams internals. Also, the MBX feed lips look more like SV so I would not use STI dimensions to judge if yours are out of spec. Ask MBX what the correct dimensions should be.

[CJDOUBLETAP]

I'll have to try some grams springs and followers in them. Thanks for the tip.

 

My load is a 125gr Zero JHP loaded 1.235 long.

 

I have sent the same pictures to MBX. They say its a stacking issue and recommend a 1.225 OAL. I'm skeptical that a .010 change in the OAL will solve the problem, but I'm going to try it tomorrow.

[MrPostman]

Had the same problem with my CZ Czechmate mags, in order to tune them so they would work I had to squeeze the control ridge on the mags at the top to close the top more so the bullets would start into a single stack earlier which is needed to support the top round. If you look at your mags from the top you can see the one on the right is squeezed together much more than the one on the left. Idealy you want them squeezed together to where the feed lips conform to the follower about one round down from the top.

 

I used a couple of small allen wrenches that were the same width as the control ridge and put those on both sides were it starts tapering, then I put that in my vise with the vise squeezing the lower part of the allen wrenches into the mag, then I grab the ends of the wrenches at the top and squeeze them together with my fingers.

You will need to measure the mag that works at the top and make the others the same.

 

My mags were about .560" wide at the control ridge, I needed to close them down to .510 - .515 for them to feed properly. After doing this then you need to retune the feedlips inside measurement to .350" - .355" at the rear of the mag and .355" - .360" at the front, you want .005" wider at the front so the rounds are tilted up slightly. Good luck

 

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

 

 

 

 

 

 

 

 

 

 

 

[orangeman711]

I have had zero problems with my MBX mags in 9mm Maj. 38 Super and Sc,and 40 cal.

[CJDOUBLETAP]

27 minutes ago, MrPostman said:

Had the same problem with my CZ Czechmate mags, in order to tune them so they would work I had to squeeze the control ridge on the mags at the top to close the top more so the bullets would start into a single stack earlier which is needed to support the top round. If you look at your mags from the top you can see the one on the right is squeezed together much more than the one on the left. Idealy you want them squeezed together to where the feed lips conform to the follower about one round down from the top.

 

I used a couple of small allen wrenches that were the same width as the control ridge and put those on both sides were it starts tapering, then I put that in my vise with the vise squeezing the lower part of the allen wrenches into the mag, then I grab the ends of the wrenches at the top and squeeze them together with my fingers.

You will need to measure the mag that works at the top and make the others the same.

 

My mags were about .560" wide at the control ridge, I needed to close them down to .510 - .515 for them to feed properly. After doing this then you need to retune the feedlips inside measurement to .350" - .355" at the rear of the mag and .355" - .360" at the front, you want .005" wider at the front so the rounds are tilted up slightly. Good luck

 

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

 

 

 

 

 

 

 

 

 

 

 

Nice. Hopefully I can figure something else out, but I may have to go this route. I've tuned STI mags in the past with good luck. I just buy the MBX mags for the capacity.

 

Thanks!

[CJDOUBLETAP]

8 minutes ago, orangeman711 said:

I have had zero problems with my MBX mags in 9mm Maj. 38 Super and Sc,and 40 cal.

All I shoot in limited is the MBX mags. They are awesome and I've had no problems. I've also had no problems with the old style MBX tubes in .38 super, its just the new tubes I'm having trouble with..

[hdgun]

I have an older Bedel and an STI/SV. I use MBX 38 super and have the same stacking issue. But,  they run in both guns. 

38 super zero jhp 1.235"

[redfisher]

I threw the towel in on 38 super. Super comp has been running perfectly since I switched over.

[Sporky]

I had the same issue. Switched to comp and it was good to go.i still have a bunch of super brass I would like to shoot up. I wish they would figure this out

Sent from my SM-G930V using Tapatalk

[MrPostman]

I threw the towel in on 38 super. Super comp has been running perfectly since I switched over.

I never had a problem with regular 38 super in my STI, the problem is not the brass but the magazine body not being tuned correctly.

Sent from my SAMSUNG-SM-G935A using Tapatalk

[redfisher]

Just now, MrPostman said:

I never had a problem with regular 38 super in my STI, the problem is not the brass but the magazine body not being tuned correctly.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

I would agree that the mags can be tuned to handle it better . . . BUT, the round wasn't designed for a double stack mag, I shot it for years in a caspian wide body with no issue, but eliminating the rim eliminates a big variable.

[MrPostman]

I would agree that the mags can be tuned to handle it better . . . BUT, the round wasn't designed for a double stack mag, I shot it for years in a caspian wide body with no issue, but eliminating the rim eliminates a big variable.

I agree that 38 supercomp or TJ brass is better as far as reliability since the rim is smaller, they do tend to stack better in a double stack mag. I used regular 38 super in my MBX mags and never had an issue so it can be done. It still all boils down to mag tuning.

Sent from my SAMSUNG-SM-G935A using Tapatalk

[RaylanGivens]

On 6/16/2017 at 11:00 AM, jcc7x7 said:

It's a good idea, and I normally do it when I build one, to bevel the bottom of the ramp so there isn't a sharp edge. You might try that and see if it solves the problem and it shouldn't cause any etc!

 

I'm trying to visualize how beveling the bottom of the barrel ramp would help direct rounds into the chamber...  instead of wedging against the barrel ramp.

 

It seems like beveling the barrel ramp would make a round more likely to go off the side of the ramp, instead of into the chamber...  unless you mean that you widen the actual ramp...  What am I missing?

[jcc7x7]

You're beveling the bottom of the ramp.  Where the ramp transitions into the magazine opening.

So as the rounds come up the mag tube, "IF", they hit the bottom of the ramp they slide over it and are lined up with the ramp.

VS.

Hitting the bottom edge of the ramp and hanging up there, causing what appears to be a nose dive into the ramp.

Usually solve by one of several changes that can help or alleviate the problem.

1. bevel bottom of ramp

and / or load longer OAL rounds, Put new guts in the mag tube and tune said tube, find a bullet the gun likes (i.e. will feed without problems)

 

As an example one of my guns would feed anything out of an old set of SV mags but wouldn't feed any of the same rounds out of my STI mags.

Final fix was new springs and followers, Tune mag lips and change from flat points bullets to hollow points with a smaller ogive or RN bullets