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saltydecimator

shells deforming in extractor groove, failure to feed. (tristar s-12 clone)

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i found an old post from md talking about how to file on the groove a bit, but i smoothed it out a bit and still getting issues... any thoughts?  too thick of a shell rim on the barrel?  wrong angles on the extractor and barrrel groove?   magazine follower angle wrong?  mag catch face too low?

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Try loading a mag and marking the top of each shell.  Then fire, and recover.  When you know the angle of the deformation from top, then you know where to start looking. 

My first S12 had a narrow trunnion on the extractor side and would deform the lip pretty bad on ejection (shear it off almost).

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What was your fix? I’m not fully following. Fingers type faster than brain haha 

 

So did some work on it yesterday... when I was trying to get pictures I had the great idea to turn it over to take picture. It’s deforming on the extractor groove, aaaaaaand the lower 5-7 o’clock groove. So never would have thought of that if evl hadn’t asked for pics. So, thanks!  Now I just need to get itsmoothed enough to be 99-100%. If that’s even possible

 

Well shoot looking at pics it’s not the grooves it’s the chamber lip. I gotta resize pics n post standby

66015A06-4056-4334-9F29-D18558EC74E0.jpeg

Edited by saltydecimator

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In the top pic, it looks like that shell had been ran through more than once and possibly caught on the extractor slot on the first go or a previous go (the bulge on the right at the feedramp, in relation to the pic, not the right of the weapon). If what I think I am seeing is what I am really seeing, they basically skipped a step at the chamber end or decided that it didn't matter enough to copy. Maybe they tested the early ones with very stiff-hulled loads and it simply wasn't an issue that needed to be addressed, from their perspective.

In this pic, the grayish pink is what I think is the area where the rim fits into the chamber. If it is (key word 'if'), you might try taking a little from the slot into the chamber beyond where the rim goes (green area). File, check, repeat as necessary until it no longer hangs there. Worst case, you get a little carried away and the case heads bulge at the slot because you went to far. As long as you do not go crazy, a little bulging should not affect safety or extraction, but may effect the viability and/or safety of reloading the hulls that you fire. I play a gunsmith on youtube, use your head... save your eyes and hands ;)

 

A0AB683F-46DA-45BC-8353-23503D5E3F97.thumb.jpeg.7c68bb718abfb9d43c02fd6d9ff9dd92HELP.jpg

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loooolz, something about kitchen wizards??

 

i took some off from the green area, by off, i mean i smoothed the top and bottom side a bit, as well as that lower slot ( is that for machining purposes, or what is its function?).  runs better now.... been 25rds of universal without a failure... notta lot i know, but i think i gotta send it in as the bolt carrier has daylight showing through the recoil spring tunnel.  whoooops!

 

 

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I think that would run perfectly if you change your technique slightly. Get more mass behind the weapon. With the shoulders angled and the butt in the 'pocket', there just isn't much mass behind the weapon. I know it may sound nuts, but I put the butt on the collar bone (almost directly below the side of the chin) with the shoulders very close to square to the weapon. Lean your entire torso forward until you feel the butt flat on the collar bone and pull the weapon in tight (looks like you are doing a good job of that part already). There is also less flesh there, which reduces soreness and bruising if you are doing it right. You may have seen it already, but I have a video on youtube with 'Long Gun Shooting Technique' in the title. Have a look if you haven't already or if you could use a refresher. 

 

That carrier situation is interesting. I would be concerned about cracking in the areas around that milled out area that initiates bolt lockup. It would be interesting to see how long it lasts or if it cracks elsewhere as a result of deficient material in that area. That area isn't very thick in the Russian guns, but I am sure that it adds some level of durability.

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it never occurred to me how thin that area may be, until i  saw these voids.  positive note is that they gonna warranty it, even though i been working on it... its kind of a big, main component, and if it shattered and blew shrapnel all over,  i suppose they would have potential liability on their hands...

 

as far as technique goes, i shall try that in the future,  that stock wasnt actually mounted to trunnion at all.  and the angle of it is kinda wrong. 

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I don't understand how such a basic concept like making the comb of a stock inline with the bore is so hard to understand for these manufacturers. One thing that I like about ARs is there isn't much chance to goof up the comb angle, lol.

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So why is the russki fixed and folders at that less than ideal angle? 

 

Im debating de riveting this fixed folder trunnion but it’s my only “stock “ configuration v12. I guess I could always get another...

 

good news, tristar warranting that carrier. Sent gun off on Tuesday. Hopefully their gunsmiths will treat me right 

3EFBF213-976B-480F-AFF9-792A257B76DC.jpeg

Edited by saltydecimator

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Leave the trunnion, change the angle of the stock. Make it WARSAW length and get rid of that nonsensical cheek rest. It has been done and is an improvement.

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On 2/13/2019 at 4:46 AM, evlblkwpnz said:

I think that would run perfectly if you change your technique slightly.

 

Who wants a gun that only works reliably when your technique is perfect? These are gas operated for a reason. You need them most when the human is least likely to be working properly.

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11 hours ago, gunfun said:

 

Who wants a gun that only works reliably when your technique is perfect? These are gas operated for a reason. You need them most when the human is least likely to be working properly.

If he doesn't want to work on it or send it out for work it is a very easy way to make it run well. If he is using it for more than gun fun it needs work ;) I try to avoid the "I'll make that run great for you for $$$". Also, I'd like to think people aren't using the cheapest loads they can find as HD ammo.

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hahaha excellent points folks!   naw not gonna put money into turkish trash dump, hahahaah.... cause once it runs nice with "sound" parts, i expect it to catastrophically fail in a different spot....

 

i need to look up that vepr change you talkin about, that sounds bad ass!

 

dang tube stock so heavy though! almost 150% heavier than wood!

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