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Posted: 9/10/2025 9:01:21 PM EDT
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This is on a rifle I've owned for 15+ years, never had any problems. Stock, no modifications. Hadn't shot it in probably 3+ years. I did re-oil it back in Feb/Mar of this year. Took it out to shoot two days ago, and it wouldn't fully chamber the first round. I was using 20 rd PMAGs, that I've used before. The bolt would stop with about 1/4" or slightly less from being fully chambered. I tried using the forward assist but it didn't work. Tried multiple times, couldn't get it to properly chamber a round. No debris in the breech area. I even put a small drop of oil on the bolt right next to the cam pin area, and also a drop or two behind the "fins" of the bolt face, and wiped off excess oil. Tried sliding the bolt in/out of the carrier. Still wouldn't chamber a round. I swapped the complete charging handle and BCG with another rifle and it chambered and fired just fine. Watched a couple videos on youtube and one guy suggested taking the bolt out of the carrier, then removing the extractor from the bolt. On the inside of the extractor, he said to remove the o-ring. Has anyone heard of doing this, in my scenario? Is that a legit fix for this? I figure I might buy a new o-ring for this bolt/extractor if removing the old one seems to fix the issue (if it's even a good idea). |
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Originally Posted By DD1801: Feb/Mar of this year. Originally Posted By DD1801: Originally Posted By backbencher: When's the last time you've cleaned it? Feb/Mar of this year. Now that you've taken the BCG apart & put it back together, does it work now? |
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Originally Posted By backbencher: Now that you've taken the BCG apart & put it back together, does it work now? Originally Posted By backbencher: Originally Posted By DD1801: Originally Posted By backbencher: When's the last time you've cleaned it? Feb/Mar of this year. Now that you've taken the BCG apart & put it back together, does it work now? Haven’t a chance since I shot it. |
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Originally Posted By RD20: If the bolt wouldn't rotate by hand after you pulled it and then put it back in, it sounds like possibly you didn't seat the firing pin fully before you put it's retaining pin back in last time you were maintaining it. Just a guess. It rotated just fine. Originally Posted By Kangbeef: New factory ammo or reloads. New factory ammo. Originally Posted By lysanderxiii: Originally Posted By Joedirt199: Have heard of the orings hardening over time and making the extractor so stiff it would not click over the case rim. May be the issue. Take the o-ring out and throw it away. Think that might be the 2nd easiest trouble shooting I can try out. I'll probably order a few soon. |
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Originally Posted By Joedirt199: Have heard of the orings hardening over time and making the extractor so stiff it would not click over the case rim. May be the issue. This, and could be if O ring is used over extractor spring for extra tension, O ring has hardened up. Also, pull the bolt off the carrier, dry fit the carrier in upper with it key, and see if gas tube is still indexed to gas tube. Also, with carrier in hand, check inside of key channel, since may have had a blow primer and piece of it wedged in carrier key channel now. From there quick check last of chamber neck cut,since may have had a case neck ring break off and still stuck in last of chamber. And lastly for quick checks, if reloads, check ammo with ammo gauge,since may have a problem with round not trimmed correctly, over bullet crimped to budge shoulder of case to no longer be fully sized, or bullet could be long loaded, and you have bullet engaging rifling on loading. Note on bullet embedding, make sure to pull B/C with upper shotgun opened, to look down bore/run a cleaning rod down the bore and make sure you don't have a loose bullet stuck in the bore throat to start with. |
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'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
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Originally Posted By Joedirt199: Have heard of the orings hardening over time and making the extractor so stiff it would not click over the case rim. May be the issue. For non-full automatic AR-15s, o-rings cause more problems than they fix. Always remove o-rings. If you feel you have to do something just make sure you have extractor springs that are 4 coil, made from 0.025"-0.026" diameter wire. |
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Originally Posted By borderpatrol: Reloads? If so, you need to bump the shoulder back some more. AR-15's need .003" of cartridge headspace clearance for reliable feeding and function. Originally Posted By borderpatrol: Reloads? If so, you need to bump the shoulder back some more. AR-15's need .003" of cartridge headspace clearance for reliable feeding and function. Nope, all factory ammo. Originally Posted By lysanderxiii: For non-full automatic AR-15s, o-rings cause more problems than they fix. Always remove o-rings. If you feel you have to do something just make sure you have extractor springs that are 4 coil, made from 0.025"-0.026" diameter wire. I'm not in the tech forum a lot, but that's the first time I've heard this. Been busy with work/family, so I haven't had a chance to try any trouble shooting. Still planning on ordering a 10-pack of O-rings from brownells. |
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Ok, so I tried removing the extractor O-ring, then re-assembling everything but it is still not fully chambering a round. I tried another complete bolt carrier group from another rifle into this upper and it chambered a round just fine. (Upper is not the problem). So I swapped the two bolts out, but still used the same original bolt carrier group, and this time it chambered a round just fine. (This tells me the bolt carrier is fine). If I tried the malfunctioning bolt into a different bolt carrier, it still would not fully chamber a round. I think there is something wrong with the bolt. If I compare the two bolts, it looks like the ejector pin is deeper into the bolt face of the bolt that is malfunctioning. Could this be related to the issue? See pictures below. The malfunctioning bolt is the one on the left. The good bolt is the one on the right. Edit - I just tried pushing on the malfunctioning bolt's ejector, and it has zero play, won't budge. I am able to push the working bolt's ejector in and it returns to normal when I let go. Looks like that might be the problem here (ejector, ejector spring, roll pin, or some combination of the three) . Now to order an ejector tool. My 1/16" punch won't drive the ejector pin out.  
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Originally Posted By DD1801: I'd get a Sinclair AR-15 Bolt Vice , it's the best $20 I ever spent on AR-15 related tools. It makes removing/re-installing the ejector super easy. Also I got a bag of 1/16"x6/16" coiled spring pins from zoro for $12 (these are 1/16" shorter than mil-spec which is 7/16" in length but I found they're easier to install without any tips sticking out on one side or the other). These are reusable unlike the c shaped roll pins which are supposed to be tossed once you remove them the first time b/c they don't keep their tension as well. |
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Originally Posted By lysanderxiii: Take the o-ring out and throw it away. Originally Posted By lysanderxiii: Originally Posted By Joedirt199: Have heard of the orings hardening over time and making the extractor so stiff it would not click over the case rim. May be the issue. Take the o-ring out and throw it away. This. Replace with Colt copper spring and black insert. |
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I couldn’t get the ejector roll pin out. Soaked the bolt in penetrating oil. I did get the ejector to move in and out freely, but it still would not fully chamber a round. Broke/bent one 1/16” punch trying to get that roll pin out. Had to buy another. Used the Sinclair bolt vice tool, still couldn’t get the roll pin out. Screw it. Bought a new CMMG bolt from PSA on sale last month. I did have all new parts on-hand from PSA (new ejector, roll pin, spring; as well as new extractor o-rings), but for now they’ll just go in my spare parts stash. |
The Emperor is naked.
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Originally Posted By DD1801: I couldn’t get the ejector roll pin out. Soaked the bolt in penetrating oil. I did get the ejector to move in and out freely, but it still would not fully chamber a round. Broke/bent one 1/16” punch trying to get that roll pin out. Had to buy another. Used the Sinclair bolt vice tool, still couldn’t get the roll pin out. Screw it. Bought a new CMMG bolt from PSA on sale last month. I did have all new parts on-hand from PSA (new ejector, roll pin, spring; as well as new extractor o-rings), but for now they’ll just go in my spare parts stash. bingo. eventually time is money for everyone. I keep a spare full bcg on hand and a full lpk and charging handle. on a long enough time scale almost everything is a consumable. |
The deuce you say.
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