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Need help finding cause of jam


MidPack
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My Tanfo Limited Custom in 40 has been jamming lately on the second round. After one round is chambered and fired the subsequent round is not being fed into the barrel. It appears the breech face is catching this round in the extractor groove and thus not being able to hook under the extractor and be fed correctly. All mags are factory K40 tubes with grams followers and springs with Henning stendos. All mags have feed lips adjusted to .386" and I experermented with stretching the springs (springs new in January 2020, beveled the breech face, polished the extractor, changed recoil springs 12,11.5,11,10 and 9lb all seem to do it 9lb the least but had other issues at that point. Ran my mags in a friend's Stock II and had no issues. Loading to 1.130" 

 

Here's some links to the pictures from today's range session.

Photo1

Photo2 

Photo3 

 

Thanks for any input in advance 

Dave

 

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I'm not overly familiar with these guns, but it seems it would relate to either the slide stroke - as in not going far enough back to allow the magazine to lift the cartridge fully.  That implies recoil spring, and you said it was less a problem with the lighter spring, seeming to indicate the less powerful spring was allowing more time before the slide started forward.  Is there any sort of shock buff or such that may be limiting the slide from going fully back?  Is the slide lightened versus your friend's slide not being lightened?

 

While the magazine springs are fairly new, do you have any stock springs you can try?  The thought being to lift the partridge quicker.

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7 hours ago, Guy Neill said:

I'm not overly familiar with these guns, but it seems it would relate to either the slide stroke - as in not going far enough back to allow the magazine to lift the cartridge fully.  That implies recoil spring, and you said it was less a problem with the lighter spring, seeming to indicate the less powerful spring was allowing more time before the slide started forward.  Is there any sort of shock buff or such that may be limiting the slide from going fully back?  Is the slide lightened versus your friend's slide not being lightened?

 

While the magazine springs are fairly new, do you have any stock springs you can try?  The thought being to lift the partridge quicker.

Thanks for the reply It has a factory lightened slide, but no shock buff and the factory recoil spring is  12lb . I have one factory mag I can try but I think it has the same issue from what I remember. 

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7 hours ago, MRevolutionIX said:

How is the tension on the extractor? Too much tension can cause this.  I experienced this when I replaced my extractor springs to extra power springs in my CZs.  

Initially that's what I was thinking until I realized the case wasn't touching the extractor before it would jam the edge of the breech face is going over the rim and into the groove in the brass. I did order a new extractor and spring to try though. Thanks and I ordered an extra power spring so I probably won't put that in as it's all ready pretty stiff

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Played with snap caps for about an hour trying to figure this out and then started tearing the gun down looking for any thing and I am starting to think the mag catch is causing the magazine to sit too low it seemed to have a good amount of free play I compared with a friend's gun and his mag has maybe a 1/3 or 1/4 of the play mine has. The mag fully pressed in does not contact the ejector but just hanging it is .066" lower and seems like that is the make it or break it for the breech to strip the round correctly. Any ideas on how to resolve this? I think I need a mag catch with a higher notch or wider notch. Links to pics and video.

 

Friends Gun with same mag combo less magwell 

 

My gun showing more play 

 

Mag catch, no wear besides the finish.

 

Hopefully someone has seen something like this or can tell me if I'm headed in the right direction. 

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Yes, hold the mag up from the bottom and cycle slide.  If it feeds then it's the mag catch.  Another symptom is the bullet jams into the frame feed ramp because it is too low and won't  transition out of the feed lips.  Doesn't happen often, but it does.

 

edit:  Measure the mag catch slot on the mag tube

Edited by 38super
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1 hour ago, 38super said:

Yes, hold the mag up from the bottom and cycle slide.  If it feeds then it's the mag catch.  Another symptom is the bullet jams into the frame feed ramp because it is too low and won't  transition out of the feed lips.  Doesn't happen often, but it does.

 

edit:  Measure the mag catch slot on the mag tube

.125 - .126 on 6 mags 

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42 minutes ago, yigal said:

good pic. of the feed rump will help. i hope  it looks like this .

SIII feed ramp chip and burr - Tanfoglio (EAA / IFG) - Brian ...

Yeah looks like that, I put it next to another 40 barrel to see if the angle was off or if anything was different and it all looked the same.

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Gun is definatly not short stroking, barrel has edges broke and ramp polished to a mirror finish, but this is what I have come up with... 

My mag catch 

 

Same style mag catch picture from google

 

Compare the thickness of the catch surfaces mine is very skinny allowing a lot of play and the other one looks to be almost the size of the mag catch hole in the mag. 

 

I ordered a new mag catch from Patriot Defense so I guess we'll see when it gets here if it changes anything.

Edited by MidPack
Added update
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4 minutes ago, yigal said:

new from the factory with this mag release ?

Yes, Bought it late November 2019 Might of been December when. I picked it up from the FFL 5k rounds through it fighting this issue most of the way and has been becoming more frequent. 

Edited by MidPack
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1 hour ago, MidPack said:

Yes, Bought it late November 2019 Might of been December when. I picked it up from the FFL 5k rounds through it fighting this issue most of the way and has been becoming more frequent. 

i hope it will solve your problem. enjoy your new gun. it's one of the best.

 

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Update: New Mag catch installed, ran flawlessly through 200 rounds through 5 different magazines without a hiccup. 

Here is a comparison of the mag catches

 

The bad mag catch is on the left the replacement on the right. Hopefully if anything this will help someone if they have a similar issue. 

 

I did reach out to EAA customer service and they would not send a replacement part without sending the whole gun in on my dime and waiting for them to evaluate and repair. Which for me isn't going to work now that it's fixed and local matches are finally about to start if pending on the kung-flu.

 

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