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ehowell12

Jam That Won't Die -- Please Help!!

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Posted (edited)

The gap between the top round and the one under it allows the top round to nosedive. This is an inherent problem with single stack magazines and is explained at this link:    https://americanhandgunner.com/gear/nosedive-and-feed-angle-in-the-1911-45-acp/

 

The gap can be eliminated in double stack magazines if they are designed correctly. If not, the gap is still there. The trick with double stack mags is that they have to transition from double stack to single stack and prevent that gap from appearing. I haven't seen MBX magazines so I can't comment on this, but if the gap is present, that is a big part of the problem.

 

Para Ordnance solved this in their 9mm double stack mags by starting the transition groove lower in their mag body. Para Ordnance has two magazines, one for 38 Super and one for 9mm. The 38 Super magazine would allow the gap, but their 9mm magazine does not and it's all because their transition groove in the 9mm magazine starts lower in the magazine body. 

 

 

AllParaMags.jpg

GappicturesinParaMags.jpg

 

 

 

Try FMJ round nose bullets. The Blazer might have failed simply because they are plated bullets, which are very soft. You want to try it with a true FMJ RN bullet.

 

Edited by superdude

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1 hour ago, ehowell12 said:

 

I'm assuming that the dimension called in the Atlas video for STI Gen 2 mags would be the same for MBX mags? 

Dunno. I am not a mag slut. I have SPS tubes tuned by Beven Grams. They just work. 😉

 

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I think your mag feed lips are to tight. open them up to .350-.355 this is the specs that Dawson gives.

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What about a mag catch that holds the mags a touch higher like the Dawson...?

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2 hours ago, sauza45 said:

I think your mag feed lips are to tight. open them up to .350-.355 this is the specs that Dawson gives.

For 38/9mm I tune mine .355 

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4 hours ago, sauza45 said:

I think your mag feed lips are to tight. open them up to .350-.355 this is the specs that Dawson gives.

.350 makes the gap between the first and second rounds much, much worse. Compounding the nosdiving issue. 

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2 hours ago, wgj3 said:

What about a mag catch that holds the mags a touch higher like the Dawson...?

The E2 grip is a proprietary mag catch I believe. Another may work, but there may be other problems arise. 

Something to look into for sure! 

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Make sure when the mag is inserted with slide back, that the round does not touch the underside of the ejector. 

 

I have fixed three guns this week alone that had the same issue. Ejector wasn’t letting round sit at an ideal angle and also would hold the round down when the feed lips were trying to release the bullet.

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16 hours ago, ehowell12 said:

 

I tend to agree, but I can't prove it! 

 

i know few pro that can help . few minutes and  mags will admit.😉

i hope u use new mag springs. and i hope that ejector don't interrupt mag function properly.

 

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16 hours ago, ehowell12 said:

 

I tend to agree, but I can't prove it! 

All mags vary in age, with the 155s being oldest. They seem to cause more problems that the 170s, but only two of the 170s are relatively new. All mags have caused issues on multiple occasions.

I'll report back after I check all the mags per the above Atlas video. 

Although it is weird ALL the mags you have tried have malfunctions which tends to make me think something in the gun itself is the culprit

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15 hours ago, CHA-LEE said:

This might be way off in left field, but looking at the very first picture it shows the ejector prong is sticking out past the breach face when the round is in the "jammed" condition. The rim of the case might be hitting or binding up on the tip of the ejector as it tries to climb up the breach face during the feeding process because it is too long. Try using an ejector with a shorter prong and see if that solves the issue. They are cheap and easy to fit.

I noticed that too, but didnt know what it was.

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My load is the same 115 PD and HS6.  I run a OAL of 1.173.   EGW U die,  mixed brass.

 

What works for me with MBX mags--YMMV.       Set the feed lips around .342 at the back,  .350 at the front.

I set mine so the bullet contacts the feedramp about 2/3 of the way up.  

Whack the loaded 170 mag base on a flat surface.  Shake and listen.  If it rattles at all it will do a nose dive

malfunction about halfway empty.   Weird.   No problem with 140's,   no experience with 155's.

Looke at the front of the mag and see if the feedramp is hitting it.   KKM barrels will hit.   Schuemann does

not.  Trim feedramp as needed.

 

 

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Are you using an Uplula? I found that they tend to push the previously loaded round forward when inserting the current round. This leads to the rounds nose diving. I only use my hands now when loading mags and I make sure that the 2nd round is pushed fully back to the end of the tube.

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On 8/27/2019 at 4:12 PM, CHA-LEE said:

This might be way off in left field, but looking at the very first picture it shows the ejector prong is sticking out past the breach face when the round is in the "jammed" condition. The rim of the case might be hitting or binding up on the tip of the ejector as it tries to climb up the breach face during the feeding process because it is too long. Try using an ejector with a shorter prong and see if that solves the issue. They are cheap and easy to fit.

We'll take a closer look at this for sure. Thanks!!

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Posted (edited)
5 hours ago, lacivilian said:

Are you using an Uplula? I found that they tend to push the previously loaded round forward when inserting the current round. This leads to the rounds nose diving. I only use my hands now when loading mags and I make sure that the 2nd round is pushed fully back to the end of the tube.

Yes, I do use an uplula, and I've noticed that as well. I do make sure that all rounds are against the back of the mag to begin with but stopping every 5-8 rounds and inspecting / tapping the tube on a table.

Edited by ehowell12

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All mags will likely be going back to MBX soon for testing / inspection. There is a significant gap between the first and second rounds. Hopefully that's the culprit!

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When properly set up, most guns are relatively insensitive to magazine tolerances, ie. feed lips, springs and followers.  If every mag you're putting in the gun exhibits the same failures, it's not the magazines.  Have you tried the same magazines in another gun?  If possible try them with your ammo.  If they run in different guns, the problem is with your gun.

 

I would suspect, in order of likely hood:

The ejector is too long or too low

The edge of the breachface is too sharp, and is dragging the second round forward

The magazine catch is holding the magazine too high

The feed ramp is too far back or too low

The extractor is too tight or has a sharp edge that digs into the case

 

Nolan

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Posted (edited)
1 hour ago, Nolan said:

When properly set up, most guns are relatively insensitive to magazine tolerances, ie. feed lips, springs and followers.  If every mag you're putting in the gun exhibits the same failures, it's not the magazines.  Have you tried the same magazines in another gun?  If possible try them with your ammo.  If they run in different guns, the problem is with your gun.

 

I would suspect, in order of likely hood:

The ejector is too long or too low

The edge of the breachface is too sharp, and is dragging the second round forward

The magazine catch is holding the magazine too high

The feed ramp is too far back or too low

The extractor is too tight or has a sharp edge that digs into the case

 

Nolan

 

I second most of this.  The gap under the first round in the mag is not a deal breaker.  It's very hard to get rid of it 100% with 9mm because of the tapered case.  The good news is this should not cause the gun not to run.  

 

For clean feeding all the geometry needs to be right and everything needs to be as slick and smooth as possible.  Definitely make sure the edge of the breech face is not sharp.  I slightly round mine and polish it smooth.  Same goes for the extractor, be sure there are no burrs and it is radiused and smooth.  Too much extractor tension can be hell on feeding rounds as well.

 

The rest of the geometry revolves around the location of the mag in the gun as well as the feed lips.  Your feeds lips are close, I do most at .350" front and .005"-.010" less in the rear with good luck.  I sand and polish my feed lips more often than I reset their dimensions.  You should try another mag catch or modify yours and try the mags sitting both lower and higher depending on where you are.  This can be a big deal with some guns considering the stacking of tolerances between frame, grip, mag catches, and magazines.  

 

Some combination of the above factors should fix you.

Edited by theWacoKid

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Posted (edited)

Press the magazine base down onto a table while hand cycling through a magazine. This will force the magazine to sit higher in the gun during cycling. If the rounds all cycle correctly the problem is likely to be the height of the magazine catch is too low.

 

A simple test to eliminate one possible issue.

Edited by DownUnder

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23 hours ago, mach1soldier said:

Make sure when the mag is inserted with slide back, that the round does not touch the underside of the ejector. 

 

I have fixed three guns this week alone that had the same issue. Ejector wasn’t letting round sit at an ideal angle and also would hold the round down when the feed lips were trying to release the bullet.

This is a common cause of nose dive feed malfs in 2011 guns...  I check for it by pulling the slide off and inserting a loaded mag. First the round should not be touching the bottom of the ejector at all at rest. Then push the loaded round out of the mag. Look to make sure as the round slides out of the mag it doesn't touch the bottom of the ejector. Chalee's suggestion is also a good one I've seen issues with the ejector nose being too long with respect to where the round is released from the feed lips.

Tolerance (in grips and mag release shelf height and ejector dimension) can cause mags that work in one gun to exhibit this problem in another gun.

 

If you are going to be at Brocks gap (I think they are having a match in Sept?) I can let you try some of my sv mags to see if it makes any difference.

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On 8/27/2019 at 2:47 PM, konkapot said:

I had the same problem 8+ years ago shooting singlestick; didn't  create a feedway malfunction but did make it impossible to drop a loaded mag out of the gun. 

 

I finally just switched divisions out  of frustration, but I hypothesized at the time that the magazine spring was weak, and allowed the top round to get pushed forward by the slide as it went into battery. My solution would have been new magazine springs. 

^^^^^^^this.  Just for giggles.  Buy  one stock STI 140mm mag.  Add an ISMI 11 coil spring and see if your issue goes away.  The ISMI springs are about 4" longer than the stock STI 11 coil springs.  It made my nose down FTFs go away.

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39 minutes ago, caspian guy said:

If you are going to be at Brocks gap (I think they are having a match in Sept?) I can let you try some of my sv mags to see if it makes any difference.

Thanks! I'll check those things out for sure.

I won't be there in Sept, I'll be shooting GA State of not in Open in CO. I do definitely want to try some of those though! 

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1 hour ago, ehowell12 said:

Thanks! I'll check those things out for sure.

I won't be there in Sept, I'll be shooting GA State of not in Open in CO. I do definitely want to try some of those though! 

Good luck at GA. We'll catch up at some point. If you don't have it figured out by then I'll be glad to look at it for you/let you try some other mag setup variations.

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Is there any chance that the recoil spring isn't trimmed correctly and that's not allowing the slide to travel back far enough to give the round time/space to move up to be loaded? 

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