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


ehowell12

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Hi all, 

I've been battling an issue for a few months now on a new open gun, and I'm very close to being totally out of ideas. I need the help of those more experienced than I!! 🙏

 

I've fought this nose-diving into/under the feed ramp issue (see attached photos) intermittently (1/2 times per match) for about 8k rounds, and now, for a reason I have yet to find, I can't get through a mag without a malfunction. The malfunction seems to happen when a round moves slightly off of the back of the mag when the slide is cycling. The photos are actual, live-fire, malfunctions - not re-created at the kitchen table. I've also been working closely with the builder throughout the process, and we're both running out of ideas on what is the true cause of this.  

 

Has anyone else experienced this issue? If so, what was the fix? 

 

Gun

5" KKM Barrel, 9mm Major

CFD 3 port Comp w/ 2x 3/16" holes

Cheely E2 Grip, CK Frame, Brazos slide

Shielded Safeties - no thumb-to-slide contact possible.

 

Mags

All MBX, 3x170mm and 3x155mm

155s have factory MBX followers

170s have TTI Ultrathin followers - these seem to work better than the factory MBX, but not 100% in my case.

Issue seems to compound when a round moves off of the back of the mag when the slide is cycling. 

 

Ammo

115gr PD JHP, 115gr Everglades RN JHP, 115gr Hornady XTP

All with 8.6gr-8.7gr HS6 (170-172 pf)

Lengths from 1.15" to 1.17" (Intentionally adjusted - that's not my acceptable tolerance for OAL) 

Primers: Remington SP, S&B SP, and CCI 550 Magnum SP tried - no change.

All passes the plunk test no problem, and case gagues in my Hundo easily. (Mighty Armory size die)

 

Things that have been changed with little to no improvement:

Mag Springs - Factory MBX and Grams - I've tried old, kinda new, and brand new - to no avail. (all 13 coil).

Followers - TTI, factory MBX, TTI Ultrathin. The TTI Ultrathins feel the best when loading and thumbing rounds out of the mag.

Feed Lips - All are, and remain at 0.345" -0.348" per MBX specs for 9mm.

Recoil Spring - I've tried (all are Wolff springs) 10lb, 9lb, 10lb variable, 7lb, and a 8lb variable. The 7lb and 8lb variable were with with one aluma-buff. I'd like to stay with the 8lb variable and one aluma-buff. 

OAL of Cartridge - from 1.15" to 1.17" as mentioned above.

Extractor - Went from Caspian to EGW HD. Caspian was causing extraction issues, EGW HD has been flawless in that regard.  

Friend's STI Gen2 Mag - same issue.

Factory Blazer RN - OAL was 1.15", jammed like the photos 3 times out of 50 rounds. Yes, this was minor ammo. 

 

At first glance I see it to be a Mag issue, but given the history of this ..investigation.. I'm pretty much convinced that it can't be. At this point I'm willing to listen to just about any theory, however, but please spare me of the "send it back to the 'smith - it's his problem" responses, that doesn't help anyone. 

 

Thanks for reading and thanks in advance for the responses!

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Have you tried going shorter than 1.150”...just to see if it has any effect? I know you’d have to mess with your load a little, but it’s not like you have to dial it in. Just take a little powder out shorten it up and see if it runs?


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Have you tried going shorter than 1.150”...just to see if it has any effect? I know you’d have to mess with your load a little, but it’s not like you have to dial it in. Just take a little powder out shorten it up and see if it runs?


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The factory minor ammo he tried is likely shorter.

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Yes, the factory ammo was shorter, but not by much. I plan to try that, however, with 9major, getting short enough to prove the concept is likely not something I could stay with long term. 

However, it'll go on the list to try!

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Feed Lips - All are, and remain at 0.345" -0.348" per MBX specs for 9mm

 

That is narrow. Open up the front to .355-.357.  Lets it hit higher on the feed ramp.  Also deburr the underside of the lips if they are new. 

Edited by echotango
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@Furrly I'll definitely check that on my mags this afternoon!

@echotango I'll experiment with that as well. When the top round is against the back of the mag, it doesn't need much assistance from the feed ramp to go into the chamber. The problem arises when, next round gets shifted forward and nose dives a little from the slide chambering the top round. If that makes sense. 

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2 minutes ago, Rnlinebacker said:

emoji3516.pngemoji3516.pngemoji3516.png yea the angle of your bullet should be 45 degrees upward toward the barrel. in the first pic it seems your at 90 degrees almost

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 Yes, that's correct. All pics show a malfunction. 😉  The first pic the slide is not all the way back - the ejector is almost flush with the breech face. Pic 3 is the same malf from another angle. 

I'll get a picture of a loaded mag in with the slide locked back tonight, and upload that. 

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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. 

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@konkapot My 'smith and I have talked through that issue as well. That's a very common problem in the 1911 platform. That's one reason why there are so many crazy follower designs in various 1911 mags. I don't know how long they've been around, but the Chip McCormick mags and Tripp mags did a decent job fixing that - and the new hotness Wilson ETS mags do a good job as well. :cheers:

We concluded, that issue isn't what's happening here - the mags all drop free with rounds left when the above malfunction isn't happening. Additionally, every 2011 follower I've seen is made to be as thin as it can be. 

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5 minutes ago, bigboy69 said:

I think it's mag issues

 

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. 

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There is a similar issue with CZ's. What I think is happening is, the bottom of the breech face is dragging the next round forward, jamming it into the ramp, when it chambers the round before. What may work is to take a small file and break the 90 degree angle at the bottom of the breech face, to a 45 degree angle, and then polish to remove the file marks. My Shadow had this same issue, and breaking that angle absolutely 100% cured it. You don't need to take much of the 90 degree angle off, just enough to keep the breech face from catching on the lower round and dragging it forward. I'll see if I can find the thread that details what needs to be done.

 

This is the thread about modifying the breech face. While it is for a CZ, it should work for any other make as well.

 

https://czfirearms.us/index.php?topic=22862.0

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Load your mags and see if there is a gap between the top round and next to top round. If there is, your tubes need to be fixed in the area where they transition from double stack to single stack.

 

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

Edited by ehowell12
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10 minutes ago, ChuckS said:

Load your mags and see if there is a gap between the top round and next to top round. If there is, your tubes need to be fixed in the area where they transition from double stack to single stack.

 

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

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E

Is the barrel ramp sticking out into the magazine well at all?

IF so talk to your smith and have him remove metal to make it even with the grip when it is fully pushed back.

I've fought that fight before with both SS and 2011 guns.

Good fortune in solving the issue!

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Just now, jcc7x7 said:

E

Is the barrel ramp sticking out into the magazine well at all?

IF so talk to your smith and have him remove metal to make it even with the grip when it is fully pushed back.

I've fought that fight before with both SS and 2011 guns.

Good fortune in solving the issue!

 

It's not - that was one of the first things we looked at and checked out! It did look that way at first, but the round actually crashes into the flat right before the feed ramp. Most of the time it sets the bullet back. 

Thanks!

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The factory minor ammo he tried is likely shorter.

 

Sent from my SM-G973U using Tapatalk

 

 

He stated in his post that the factory blazer ammo was 1.150”

 

Sorry. Just saw you addressed that already.

 

Good luck. I know how frustrating phantom malfunctions can be. But you will get it figured out and then think about how good it will feel.

 

 

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1 minute ago, cecil said:

Have you tried RN bullets instead of hollow points ??

 

Going to! I have a case of Montana Gold 115gr CMJs on the way to play with. Hopefully they'll make it to my door by the weekend. I'm optimistic on that one. 

Factory RN Blazer didn't work - but being minor that's another can of worms. 

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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.

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