Inthebushes Posted January 1, 2018 Report Share Posted January 1, 2018 This gun has never worked well, but has a new problem. I have used it primarily as a single shot and it has never had an issue with the bolt locking back. Now, I can’t get it to lock back. AP upper, lower, bolt, parts. Adjustable gas block SLR; I removed it, cleaned it and the gas tube. Gas block alignment was perfect. Gas block adjustment functioned, fully closed to 12 clicks fully open. Had a Tubbs spring, replaced with standard spring no change. Tried a different bolt, no change. Cleaned everything, no change. Lubed everything, no change. I run a suppressor so I can’t believe it is lack of gas. Prior to this problem, 2 or 3 clicks open, would hold back on anything. Now wide open at 12 clicks will not hold back 9 out 10 times. When it does hold back, I get the following photo. When it doesn’t hold back, it will drive the empty forward and crunch the case mouth. Any ideas what I need to do next? This is not a new gun and probably has 1500-2000 rounds through it. Quote Link to comment Share on other sites More sharing options...
308kiwi Posted January 2, 2018 Report Share Posted January 2, 2018 (edited) BCG velocity too slow? Bolt catch and/or mag follower not interacting properly or bolt catch seized? Maybe just getting enough gas through the gas block and tube to unlock but not imparting enough energy into the BCG to drive it fast enough to cycle fully to the rear and pick up the bolt catch, seems strange that the ejector is not flipping the case out, would suggest the extractor has a GOOD grip on the case and the ejector is sticky? and the BCG is just travelling too slow? I'd be looking for signs of some component binding/dragging and perhaps also looking for signs gas leakage somewhere in the gas system/BCG. Is you gas block steel or alloy?, I had an AR15 that started to cycle unreliably and it turned out the gas had eroded the alloy gas block away in between the barrel bore of the gas block and the gas tube bore, creating a leak. I assume you have shot it sans suppressor to see if it cycles in a 'std' configuration? There's my 2c's for what it's worth Edited January 2, 2018 by 308kiwi Quote Link to comment Share on other sites More sharing options...
Inthebushes Posted January 2, 2018 Author Report Share Posted January 2, 2018 The gas block looked good. I tried 3 types of magazine. I blew out the bolt catch and oiled, seemed free. Hand cycled action/bolt feels smooth. I did not try without the suppressor, but I will in the morning. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted January 2, 2018 Report Share Posted January 2, 2018 It sounds like your bolt is gunked. It’s a little tedious but can be clean out. I’d replace the springs while I was in there. Ejector and extractor need some TLC. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted January 2, 2018 Report Share Posted January 2, 2018 (edited) ^+1! It amazed me how fast and how much gunk was packed into every empty space in the bolt when I started shooting suppressed. Your issues sound like what I get when it is time to clean a suppressed 308 AR. Even my 716 piston gun starts having these issues before it hits 100 rounds after cleaning, strangely my DI build lasts almost twice as long before a good cleaning is needed, so much for piston systems running cleaner. Edit: Have to add that on the 716 I have to keep turning up the gas as the round count goes up to get the bolt to catch. I haven't figured out exactly why but when I clean it up I can start back at the suppressed setting and the bolt locks back. Edited January 2, 2018 by jtallen83 details Quote Link to comment Share on other sites More sharing options...
98Z5V Posted January 2, 2018 Report Share Posted January 2, 2018 (edited) 2 hours ago, 308kiwi said: BCG velocity too slow? I think this case here is the opposite - BCG velocity too fast... What's happening to that empty case looks exactly like too much BCG speed, typically from overgassing. OP stated that's with the block 12 clicks, wide open. OP, when that happens to the brass, not clearing the chamber, what's the next round in the mag doing? Is it going into battery, or is the BCG over riding it? The ejector also needs to be removed and inspected... Edited January 2, 2018 by 98Z5V Quote Link to comment Share on other sites More sharing options...
survivalshop Posted January 2, 2018 Report Share Posted January 2, 2018 13 hours ago, Inthebushes said: Tried a different bolt, no change. Pretty much rules out the Bolt components , to a certain extent . The Photo seems to show , as has been said , slow BCG travel or an Ejector or Extractor issue . -Too slow of BCG travel will not have the quick change of direction to help eject the fired case or Ejector Spring is weak or compromised by fouling or both. -Extractor is stiff or locked in one position or too stiff of Spring pressure . - Lubricant used ,not up to job or not enough of it . - Loose Carrier Key Screws or Key not seated & leaking .( Suppressors seem to pronounce this condition ) -1500-2000 round count could have a prematurely worn component , Chamber throat erosion ? What caliber ? Have you been using this rifle as a single shot on purpose or is it because it never ran correctly ? Have you completely disassembled the Bolt components & cleaned & lubed ? Have you checked Gas Ring tension ? A lot of questions , but this is like a Detective story , since we cant put our grubby paws on it or see the rifle . There Tubb's Spring should work much better then a OEM one . Running any Rifle Suppressed is going to do all kinds of strange things to an action & one is heavy Fouling in places you don't normally see that kind of Fouling. I think you will find a Gas issue in some form & that could also be from heavy fouling .Keep us informed on your progress . Quote Link to comment Share on other sites More sharing options...
Inthebushes Posted January 2, 2018 Author Report Share Posted January 2, 2018 Just been using as a single shot because it destroys the next round. Even if it manages to get the next round into the chamber, the bullet itself has a big gouge in the jacket. Since we shoot for long range accuracy, I just load one at a time. Very accurate, but I hate the gun. I believe the gouge comes when the top round is stripped. The next round is moved forward and up enough for the lugs to smash it on the way by. I’ve tried several types of magazine, manipulated feed lips. I’ve given up on the automatic cycling. However the bolt lockup problem makes even single shot suck. It has to be something obvious, but I can’t see it. Is there a way to shoot a short video and post here? Quote Link to comment Share on other sites More sharing options...
Inthebushes Posted January 2, 2018 Author Report Share Posted January 2, 2018 I took the extractor out and cleaned and removed one o-ring, no difference. The ejector seemed strong and free, but I did not remove. If I hand cycle slow, I get the same problem. If I hand cycle fast, it ejects. Everything feels smooth and slick. Somehow, I have lost the bolt speed. Gas key is tight. I have a third bolt to try. That will eliminate bolt problem 100%. Quote Link to comment Share on other sites More sharing options...
Inthebushes Posted January 2, 2018 Author Report Share Posted January 2, 2018 Problem Solved! Although I had removed and cleaned the gas block, I did not check the actual gas port on the barrel. I removed the block again, dropped a 1/16 drill bit in the hole, spun it a couple times to clean off the edges, and put everything back together. Set the adjustable gas block on 4 clicks open, fired 4 rounds, and got 10 feet ejections at 3:00 with solid lock up each time. Maybe this will help someone in the future. Thanks everyone for the help. Quote Link to comment Share on other sites More sharing options...
AngelDeVille Posted January 2, 2018 Report Share Posted January 2, 2018 (edited) Glad it worked out! I'm getting ready to pull mine apart, I'll check the gas port on mine at the same time. No issues but, I don't think I inspected it when I did the initial assembly. Edited January 2, 2018 by AngelDeVille Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted January 2, 2018 Report Share Posted January 2, 2018 YEARS of shooing a .22lr conversion in my rifle has taught me to shoot some regular .223 afterwards, to blow out all the gunk. Sounds like the same should apply to suppressed shots. Blasting a few unsuppressed shots my help blow all the loose debris through before it settles. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted January 3, 2018 Report Share Posted January 3, 2018 19 hours ago, Robocop1051 said: YEARS of shooing a .22lr conversion in my rifle has taught me to shoot some regular .223 afterwards, to blow out all the gunk. Sounds like the same should apply to suppressed shots. Blasting a few unsuppressed shots my help blow all the loose debris through before it settles. Or just disassemble & clean more often when using suppressed , if the above doesn't work . Trials & tribulations of running suppressed semi or full auto Firearms . Quote Link to comment Share on other sites More sharing options...
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