johnbu 3 Posted September 25, 2017 Report Share Posted September 25, 2017 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! Quote Link to post Share on other sites
Heartbreaker 1,085 Posted September 25, 2017 Report Share Posted September 25, 2017 Try removing the buffer completely. It doesn't help cushion very well, since the bcg will hit sooner and harder with that ~3/8 less travel. It tends to increase bolt bounce which will actually get worse the more overgassed the gun gets. Quote Link to post Share on other sites
Lone Star Arms 2,047 Posted September 25, 2017 Report Share Posted September 25, 2017 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. Quote Link to post Share on other sites
johnbu 3 Posted September 26, 2017 Author Report Share Posted September 26, 2017 (edited) Ahhhh, rats. Is there a tuning trick when using the 12 round sgm mags? Or is it just a mag spring tension issue? Edited September 26, 2017 by johnbu Quote Link to post Share on other sites
Lone Star Arms 2,047 Posted September 26, 2017 Report Share Posted September 26, 2017 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 Quote Link to post Share on other sites
johnbu 3 Posted September 26, 2017 Author Report Share Posted September 26, 2017 Thanks. Quote Link to post Share on other sites
johnbu 3 Posted September 28, 2017 Author Report Share Posted September 28, 2017 Update: Hand cycled the action w mag inserted and found a few areas of rub. Corrected and also tweaked the buffer for longer slide action. Now its cycling walmart federal ($19.56 / 100) ammo on gas setting 3 of 4. And last round is ejecting. Quote Link to post Share on other sites
johnbu 3 Posted September 28, 2017 Author Report Share Posted September 28, 2017 Dang, spoke too soon. Last round...the magazine is up into the receiver slightly too high and is knocking the spent case off the extractor on the way back. Why only one the last round? Dunno! Does anyone make a mag hold that is slightly longer? Quote Link to post Share on other sites
pedal2alloy 206 Posted September 29, 2017 Report Share Posted September 29, 2017 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 Quote Link to post Share on other sites
johnbu 3 Posted September 29, 2017 Author Report Share Posted September 29, 2017 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. Quote Link to post Share on other sites
evlblkwpnz 3,418 Posted September 29, 2017 Report Share Posted September 29, 2017 Are you in NE FL, by chance? 1 Quote Link to post Share on other sites
G O B 3,516 Posted September 29, 2017 Report Share Posted September 29, 2017 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. Quote Link to post Share on other sites
johnbu 3 Posted September 29, 2017 Author Report Share Posted September 29, 2017 Are you in NE FL, by chance? No, wisconsin. Quote Link to post Share on other sites
johnbu 3 Posted September 29, 2017 Author Report Share Posted September 29, 2017 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. Quote Link to post Share on other sites
johnbu 3 Posted September 29, 2017 Author Report Share Posted September 29, 2017 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. 2 Quote Link to post Share on other sites
johnbu 3 Posted September 29, 2017 Author Report Share Posted September 29, 2017 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! Quote Link to post Share on other sites
csspecs 1,987 Posted September 29, 2017 Report Share Posted September 29, 2017 I think you may have the bolt incorrectly assembled. Quote Link to post Share on other sites
johnbu 3 Posted September 29, 2017 Author Report Share Posted September 29, 2017 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. Quote Link to post Share on other sites
evlblkwpnz 3,418 Posted September 29, 2017 Report Share Posted September 29, 2017 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. Quote Link to post Share on other sites
csspecs 1,987 Posted September 30, 2017 Report Share Posted September 30, 2017 (edited) 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 September 30, 2017 by csspecs 1 Quote Link to post Share on other sites
johnbu 3 Posted September 30, 2017 Author Report Share Posted September 30, 2017 I am hopeful the replacement part is done correctly. Will post up on how that works out. Quote Link to post Share on other sites
Lone Star Arms 2,047 Posted September 30, 2017 Report Share Posted September 30, 2017 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. 2 Quote Link to post Share on other sites
G O B 3,516 Posted September 30, 2017 Report Share Posted September 30, 2017 Amazingly 'fault tolerant' design. But that is just nasty manufactureing. Sometimes I wonder how some things ever worked! 1 Quote Link to post Share on other sites
johnbu 3 Posted October 1, 2017 Author Report Share Posted October 1, 2017 Amazingly 'fault tolerant' design. But that is just nasty manufactureing. Sometimes I wonder how some things ever worked! I agree! Hoping the replacement is much better! Quote Link to post Share on other sites
johnbu 3 Posted October 2, 2017 Author Report Share Posted October 2, 2017 Dang! Called on Friday and "ding dong" ... package on the porch. Good customer service? I'd call it great! Quote Link to post Share on other sites
johnbu 3 Posted October 2, 2017 Author Report Share Posted October 2, 2017 (edited) 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 ? Edited October 2, 2017 by johnbu Quote Link to post Share on other sites
gunfun 3,931 Posted October 6, 2017 Report Share Posted October 6, 2017 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. Quote Link to post Share on other sites
johnbu 3 Posted October 6, 2017 Author Report Share Posted October 6, 2017 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. Quote Link to post Share on other sites
gunfun 3,931 Posted October 7, 2017 Report Share Posted October 7, 2017 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. Quote Link to post Share on other sites
saltydecimator 482 Posted October 24, 2017 Report Share Posted October 24, 2017 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 Quote Link to post Share on other sites
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