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cheetah 12 - last round eject failure


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Bought a cheetah 12 on sale from "Guns Midwest" (419.00, couldn't resist).

 

Initially wouldn't cycle walmart Federal 3 dram 7 1/2 shot 2 3/4 shells. Polished up the action per this site's recommendations.... and it still wouldn't cycle them reliably. 1 or 2 would one wouldn't eject, etc. Checked with a paper clip and all 4 gas ports are open and centered no blockage from the gas block.

 

Bought CSS gas puck, reduced recoil spring, polished a bit more. Still not able to run 5. I smoothed and opened the gas plug "most gas" setting to hopefully enhance flow. (Just a little larger in case it wasn't aligned) still no love.

 

 

Inspected close and found the buffer pad was binding the action up before full stroke. Just the tip of the ejector exposed on manual rack and hold w 2 hands. Trimmed the buffer pad to allow repeatable full stroke. Now cycles back and exposes the ejector nub. Tried it out today.

 

Bam! 5 quick shots with the LAST round not ejecting. Every time.... last round does NOT get kicked out, the open end gets crumpled on the feed rails or the brass end gets caught.

 

So it cycles low federal brass, but won't kick out the last hull. Oh, this is with 12 round sgm mag.

 

 

Grrr.

 

Anyone here fought and won this battle?

 

Thanks!

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Try another mag in your gun, and make sure the gun is firmly buttressed against your shoulder when firing - really firmly buttressed. Consistent last round FTE's are usually a mag issue (especially with SGM 12 round mags). For consistency, and reliability SGM 8 rounders are hard to beat.

 

Promag 12 round drums are the best choice in terms of a 12 round mag.

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My observations are solely based upon practical experience. I cut all of my SGM 12 round mags down to 8 rounds years ago, and they continue to serve me just as well as brand new SGM 8 round mags.

 

Made no modifications to the springs.

 

YMMV

 

Mike

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The last round has the follower below, so that may be the culprit. But if that's causing interference, it is most likely that the mag is overly inserted. That could be fixed, but the easiest and cheapest solution is to get a different magazine

Happens with 2 brand new sgm 12 round magazines.

 

 

And... the gun FUBAR'ed tonight at a 3gun practice. Fail to FEED. rounds just wouldn't go into the chamber. Will have to investigate tomorrow.

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The bottom of the reciever may be bent slightly. It is sheet metal and can be straightened with a sharp rap in the opposite direction.

 

The bolt carrier seems to be worn out after 140 Federal bulk pack bird shot rounds fired. The bolt doesn't rotate and binds the action.

 

Contacting sds imports shortly.

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Contacted SDS and while thw issue is disappointing the response was refreshing. Good CS. He is sending a replacement carrier asap. He thinks it was an "old part" with a known and corrected problem. I do believe him and will update when the new "corrected" part comes in. For the record, i am optimistic!

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You can see in the one picture how loose it fits in tbe carrier. That allows the bolt to get out of the channel in the carrier on recoil and bind up.

Correct. That should fit so much tighter. That little amount of oversize in the carrier translates to quite a bit of deflection at the lugs.

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I positioned the bolt to show the "tab" that rides in the "slot" can jump out of the slot.

 

But, thank you for posting that video. It shows a lot of detail.

Oh I see it now.. Yep that is a problem.

 

Looks like the part was set in the process machine incorrectly which cause the pocket to be formed incorrectly.. It did not wear out, the part was made wrong.

Edited by csspecs
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I positioned the bolt to show the "tab" that rides in the "slot" can jump out of the slot.

 

But, thank you for posting that video. It shows a lot of detail.

Oh I see it now.. Yep that is a problem.

 

Looks like the part was set in the process machine incorrectly which cause the pocket to be formed incorrectly.. It did not wear out, the part was made wrong.

 

Gosh. I see it now. Amazing that no matter how many of these come through the door, there's always something new.

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I positioned the bolt to show the "tab" that rides in the "slot" can jump out of the slot.

 

But, thank you for posting that video. It shows a lot of detail.

Oh I see it now.. Yep that is a problem.

 

Looks like the part was set in the process machine incorrectly which cause the pocket to be formed incorrectly.. It did not wear out, the part was made wrong.

Gosh. I see it now. Amazing that no matter how many of these come through the door, there's always something new.

Hey, Mike, just noticed you are in ALBQ. We used to live over on the mesa in Rio Rancho by the Intel Plant.

 

Anyway...

 

Put the new carrier in and the gun now cycles without locking up. However, issues remain. But, I think it's magazine related more than anything. Now, I'm asking for tuning tips for the SGM 12 round magazines. The round being fed while firing will ram into the TOP of the barrel opening and hang up on the lip that the rim of the cartridge is supposed to sit in. I have a pic in my phone and will add it shortly.

 

My "assumption" is that the front of the magazine and potentially the back is sitting in a odd spot. I've read where people file material off the mags to fix issues. But, I dont want to just blindly whack away at it! LOL I'm old and dumb, but not that dumb.

 

Oh, it does it with the gas system on settings 2, 3 and 4 (4 being largest amount of gas). With no magazine in, it will eject the case on setting 2 without problem sending it 4-6 ft. In fact, it may be worse with the gas system on the most open, biggest dot, setting.

 

Unlike the real Saiga guns, the 4 gas ports are well centered and all open. Guess they don't have vodka ?

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Edited by johnbu
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Is that a failed extraction or a failed chambering?

 

Check the lips of the magazine for rub marks. If the bolt or carrier are dragging against the mag, maybe that's part of the problem. A few thou can make a big difference.

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Is that a failed extraction or a failed chambering?

 

Check the lips of the magazine for rub marks. If the bolt or carrier are dragging against the mag, maybe that's part of the problem. A few thou can make a big difference.

Thanks!

 

There does seem to be some rubbing, but it also seems to present the shells too high. They then slam into the top of the edge of the chamber entrance. Not sure of the correct terms. The shells get stopped hard enough to deform the plastic... a lot.

 

I have trimmed the mags to reduce drag and it's getting better. The factory 5 rnd seems to work fine now.

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Hmm. Sometimes deburring the area where it is snagging can help, but don't take away metal.

 

Also if the inside of the feedlips is rough, that can cause a shell to pivot upward as it is stripped. That could be the issue.

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  • 3 weeks later...

i hate to be the dbag that says, "shoulda bought a vepr", but in this case i am..... surec ou can get parts for the Chinese guns, but typically, on Russkie's, you dont NEED them... ymmv

 

i have been intruiged by tac 47, dealer in dallas has em for 450, they look like a thoughtful  clone

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