jdknotts1 Posted February 8, 2012 Share Posted February 8, 2012 I've never had any problems with this rifle. Up until the last few months, probably never had a single malfunction. The last few months I been getting two different problems. 1. Bolt will not lock back to the rear on an empty mag. And when it does, it only locks back half way. 2. Failing to fully feed. Periodically it will partially feed a round from the mag. The bolt closes half way and the round is kinked into the chamber. I tried the mags in another rifle and they work fine. I am however still getting new Wolff XP springs for all my mags, and MagPul followers. I shot two matches last year with no problems. The ONLY thing I changed was the trigger. I put a Geissele S3G in half way through FNH. Even then I didn't have any problems. This just happened recently. Here is my rifle specs: Colt 6920 16" bbl w carbine length gas "H" buffer Stock bolt and carrier Change the buffer to a different weight? Replace the buffer spring? What could be causing this? Thanks for all your advice Link to comment Share on other sites More sharing options...
releo 37 Posted February 8, 2012 Share Posted February 8, 2012 How many rounds through it? and have you checked the gas tube where it contacts the bolt carrier and made sure it's staked ? Link to comment Share on other sites More sharing options...
jdknotts1 Posted February 8, 2012 Author Share Posted February 8, 2012 (edited) I had the barrel off to put on a Troy Battle rail. I made sure the gas tube was clean throughout. And the gas key is staked. The rifle probably has approx 4-5k rounds through it. Edited February 8, 2012 by jdknotts1 Link to comment Share on other sites More sharing options...
bigbrowndog Posted February 8, 2012 Share Posted February 8, 2012 i had a geisselle trigger set, that gouged a groove thru the bottom of my carrier and caused issues with feeding and ejecting check to see if you have those issues. Trapr Link to comment Share on other sites More sharing options...
jdknotts1 Posted February 8, 2012 Author Share Posted February 8, 2012 i had a geisselle trigger set, that gouged a groove thru the bottom of my carrier and caused issues with feeding and ejecting check to see if you have those issues. Trapr There is some wear on the bottom of the carrier. Looks new but can't confirm. How would a trigger cause these problems? Don't all triggers contact the bottom of the bolt in this fashion? Link to comment Share on other sites More sharing options...
DyNo! Posted February 8, 2012 Share Posted February 8, 2012 (edited) 1. Bolt will not lock back to the rear on an empty mag. And when it does, it only locks back half way. Assuming it is not the magazine, you're either losing gas or the carrier is meeting resistance where it shouldn't be. 2. Failing to fully feed. Periodically it will partially feed a round from the mag. The bolt closes half way and the round is kinked into the chamber. What kind of magazine? Does your receiver extension match your receiver? (Feed ramp) Edited February 8, 2012 by DyNo! Link to comment Share on other sites More sharing options...
jdknotts1 Posted February 8, 2012 Author Share Posted February 8, 2012 1. Bolt will not lock back to the rear on an empty mag. And when it does, it only locks back half way. Assuming it is not the magazine, you're either losing gas or the carrier is meeting resistance where it shouldn't be. 2. Failing to fully feed. Periodically it will partially feed a round from the mag. The bolt closes half way and the round is kinked into the chamber. What kind of magazine? Does your receiver extension match your receiver? (Feed ramp) I've heard the term "matching the receiver" before but I'm not sure what exactly it means. The two groves in the barrel extension match up just as they did before I took the barrel off. Is this something I can look at and verify? I use colt 30rnd mags Link to comment Share on other sites More sharing options...
DyNo! Posted February 8, 2012 Share Posted February 8, 2012 Link to comment Share on other sites More sharing options...
jdknotts1 Posted February 8, 2012 Author Share Posted February 8, 2012 The feed ramps match up prefectly. Link to comment Share on other sites More sharing options...
Lee King Posted February 8, 2012 Share Posted February 8, 2012 Make sure the gas rings on the bolt are staggered (the gap that is). Link to comment Share on other sites More sharing options...
dqshooter Posted February 8, 2012 Share Posted February 8, 2012 Had the same malfuction. Clean the gas tube, check the gas block for fit. If it is a pinch type, it may have elongated and letting gas escape. I changed my gas tube and block and it fixed everything. I wouldn't hurt putting in new gas rings. Link to comment Share on other sites More sharing options...
MickB Posted February 8, 2012 Share Posted February 8, 2012 This is a myth. A properly built rifle should function even if the ring gaps are aligned... Mick Make sure the gas rings on the bolt are staggered (the gap that is). Link to comment Share on other sites More sharing options...
Tizzle Posted February 8, 2012 Share Posted February 8, 2012 (edited) Spend the $3 to replace the gas rings then go from there. They will wear out eventually anyway so it's basic maintenance even if it doesn't prove to be the issue. From there I would do as recommended earlier and check the new trigger/hammer assembly for excessive drag. Edited to add hammer assembly... Thanks Trapr Edited February 8, 2012 by Tizzle Link to comment Share on other sites More sharing options...
bigbrowndog Posted February 8, 2012 Share Posted February 8, 2012 it was the entire trigger set, the hammer/trigger combined. and yes the hammer contatcs the bolt carrier. Trapr Link to comment Share on other sites More sharing options...
Alaskapopo Posted February 8, 2012 Share Posted February 8, 2012 I've never had any problems with this rifle. Up until the last few months, probably never had a single malfunction. The last few months I been getting two different problems. 1. Bolt will not lock back to the rear on an empty mag. And when it does, it only locks back half way. 2. Failing to fully feed. Periodically it will partially feed a round from the mag. The bolt closes half way and the round is kinked into the chamber. I tried the mags in another rifle and they work fine. I am however still getting new Wolff XP springs for all my mags, and MagPul followers. I shot two matches last year with no problems. The ONLY thing I changed was the trigger. I put a Geissele S3G in half way through FNH. Even then I didn't have any problems. This just happened recently. Here is my rifle specs: Colt 6920 16" bbl w carbine length gas "H" buffer Stock bolt and carrier Change the buffer to a different weight? Replace the buffer spring? What could be causing this? Thanks for all your advice Have you changed anything recently like ammo. The malfunctions you are getting sounds like what I have seen when some people run Wolf Ammo. If you have not changed anything check the gas system starting with the gas tube retaining pin in the gas block to make sure its still there. Then move back to the gas tube itself make sure its locked in place, then check the carrier key on the bolt carrier make sure its tight and does not move, then check the gas rings to make sure they are still providing a tight seal. Pat Link to comment Share on other sites More sharing options...
sschultz Posted February 8, 2012 Share Posted February 8, 2012 Not sure if I missed it but try and put your old trigger group back in. I have raed some where the Geissele has caused problems with a few guns. Schultz Link to comment Share on other sites More sharing options...
DanL Posted February 8, 2012 Share Posted February 8, 2012 Josh, had this same problem a few years ago at a match in topton. Out of the clear blue on 2nd stage of match started doing this and continued for rest of match. Had armorer tear rifle down to find problem. None found but barrel ended up getting replaced because of some other problem. Did quick function check and sight in, all good. Go to next match. On first stage same problem comes back. Changed to a BCM, FA carrier cause that's what I had as spare at the time and shazzam stated working. That was 3 years ago and that is how it is still working today. Link to comment Share on other sites More sharing options...
gerritm Posted February 8, 2012 Share Posted February 8, 2012 When was the last time you completely cleaned the BCG? Scrape the carbon off the inside of the bolt carrier and at the flute end. Replace the gas rings. Sounds like you don't have consistent gas pressure. Swap out to another bcg.Check the gas key on top of the bcg and make sure it didn't come loose, should be staked. gerritm Link to comment Share on other sites More sharing options...
Alaskapopo Posted February 8, 2012 Share Posted February 8, 2012 (edited) Make sure the gas rings on the bolt are staggered (the gap that is). That is a myth the gas rings don't have to be staggered. In fact the gun will run on just one gas ring. That myth got dispelled to me when I went through my armorers school. When the bolt is inside the bolt carrier the gaps are squeezed together and closed. Pat Edited February 8, 2012 by Alaskapopo Link to comment Share on other sites More sharing options...
jdknotts1 Posted February 8, 2012 Author Share Posted February 8, 2012 (edited) Thanks everyone. I am going to tear it down and give it a REALLY good cleaning. Shoot it and see what happens. For some reason I don't doubt that its the trigger. NOTHING else has been changed on the internals. Sending the lower to Geissele. They said they will test the trigger and replace the springs to increase the trigger pull and reset. Had a lot of bump fires with it. I'll give an update if I can isolate the problem. Edited February 8, 2012 by jdknotts1 Link to comment Share on other sites More sharing options...
StealthyBlagga Posted February 9, 2012 Share Posted February 9, 2012 To check the gas rings, pull the bolt carrier assembly from the upper and stand it "bolt face down" on a flat surface. If the weight of the bolt carrier causes it to slide down over the bolt, then the gas rings need replacement. If the bolt carrier stays put, then your gas rings are probably OK. Link to comment Share on other sites More sharing options...
Alaskapopo Posted February 9, 2012 Share Posted February 9, 2012 To check the gas rings, pull the bolt carrier assembly from the upper and stand it "bolt face down" on a flat surface. If the weight of the bolt carrier causes it to slide down over the bolt, then the gas rings need replacement. If the bolt carrier stays put, then your gas rings are probably OK. That works another test I was taught is to push the bolt into the bolt carrier with nothing else and hold the bolt supporting the weight of the bolt carrier. If the bolt carrier fell off it was time for new gas rings. Pat Link to comment Share on other sites More sharing options...
Mark Gale Posted February 10, 2012 Share Posted February 10, 2012 (edited) This is a myth. A properly built rifle should function even if the ring gaps are aligned... Mick Make sure the gas rings on the bolt are staggered (the gap that is). +1 There are no gaps when the rings are compressed inside the bolt carrier. You can view a cut-a-way here Edited February 10, 2012 by Mark Gale Link to comment Share on other sites More sharing options...
Red_SC Posted February 10, 2012 Share Posted February 10, 2012 Could be the hole in the gas block not lined up with the gas port. Link to comment Share on other sites More sharing options...
Mark Gale Posted February 10, 2012 Share Posted February 10, 2012 Could be the hole in the gas block not lined up with the gas port. This is actually a rare situation. The hole in the gas block is over twice the size of the port in the barrel. Link to comment Share on other sites More sharing options...
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