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Posted: 8/5/2005 4:14:30 PM EDT
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At a recent class one of the shooters had a new Colt suffer a problem after 3-400 rounds total. The bolt carrier separated from the bolt and moved backwards enough to prevent separating the receivers, while the bolt was still forward. I could see most of the locking lugs from the breech. Is this one of the broken cam pin variations? How do you fix it, besides sending it to Colt? Also, how to prevent it? Is this a lube issue? Thanks, Rick |
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could be a broken cam pin, odd to see them shear clean enough to allow the bolt carrier to come back tho. drive the carrier into battery with the forward assist or remove the buttstock and do the same thing. you might be able to close the carrier by driving the muzzle into something solid like a block of wood but don't try that too many times or too hard. |
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Thanks, Tweak. I'm not sure what he did; probably sent the whole shebang back to Colt. It did seem weird, the cam pin would almost have to be completely separated if my mental image is accurate. I'll have a chance to ask for follow up at later classes, but won't hold my breath. A more general bolt/bolt carrier question: Are these problems "generally" due to any particular issues? I am thinking gas pressure and lubrication as top of the list. Assuming headspacing all good, big assumption. I have read the FAQs, and thanks. Rick |
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a bolt carrier with a mislocated cam pin cut could cause accelerated wear on the cam pin. an overhardened cam pin could break. to clarify, you're saying the bolt stayed forward (in battery) and the carrier moved independant of the bolt? how did the shooter find this out? |
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The bolt was forward, but not fully into battery, I could see the lugs. The carrier moved backwards enough to expose about 2/3 of the bolt . I only got to look at it for a minute. It looked to be more rearward movement than normal. Neither the bolt or the carrier could be moved with hand pressure. Could a broken lug lock up the bolt and come part way out of battery enough to expose the lugs visually and let the rearward motion of the carrier prevent opening the receiver? I would think that it would still be possible to push the carrier forward onto the bolt if that were the case. I wish I had the rifle in front of me. I'm going off of a 2 week old memory and about 1-2 minutes inspection. It doesn't sound like it's a "common" failure. Thanks, Rick |
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Here's the word I got by email from one of the instructors at the course: "For some reason the spent primer came out of the cartridge and lodged between the bolt carrier and the top of the action." I guess my memory of the bolt carrier/bolt relationship is faulty is faulty. It was way back, just not broken cam pin way back. I guess you're still looking at pulling the stock/buffer as a start at a fix. Wish I was smarter. Rick |
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