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Posted: 7/15/2012 4:59:25 PM EDT
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I built my AR a few months ago and have taken it several times cycling Federal 5.56, Tull .223, and some other no-name steel .223,, all went fine until today when I got some failures to cycle. This happened on several different lots of Tull .223. We had about 40 rnds of Federal 5.56 which cycled about half the time and would sort of loosen things up enough to successfully cycle a round or two of .223 before failing again.
It started with one .223 got jammed in the chamber and was able to be knocked out with an aluminum cleaning rod, nothing else got stuck. This was the point where we started some 5.56 tests. So my question here is what caused the bolt to stop cycling? These weren't just failures to eject caused by carbon fouling, the carrier just stayed in place. I don't see any scoring on the barrel above the gas block, and the gas tube inside the receiver has a ring of clean tube where it keys to the carrier (except maybe on the top where I can't see), but there is a lot of fouling above the tube. It's a properly staked BCM BCG and chrome barre. We'd put maybe 150 rounds through it before the first FTC, and it went to the range liberally oiled. Thoughts on cause? |
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could be gas port, could be dirty powder from the Tul, or weak powder load, anyways most of what i've read about Tul is that i should stay away from it. i've never used it, so no personal experience with it.
i've had no problem with american brass 556 or 223. i've had no problems with wolf or brown/silver bear in 223. |
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Couple of things to check out.
Cycle your bolt by hand to feel for proper function. Check out for signs of wear on the inside of your upper reciever. Check the buffer tube spring and buffer. Lube as required. If you have a second BCG drop it in for function. This will alleviate BCG problem. Original BCG carrier key could be cause if second BCG functions. Remove carrier key and reinstall. If you stand your BCG upright on the bolt and the weight of the carrier does not slide down bolt, your rings should be good. If it does slide down your bolt then replace the gas rings on your bolt. The gas block could partially be blocking the gas port on your barrel. Mark location of gas block then remove and check for blockage on barrel and gas block. Measure location of gas port/gas block alignment. Gas tube blockage. Replace with new. Just a few things to try out. I usually keep extra parts just for this reason. |
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All steel cased ammo ( except some hornady ) is under powered and will cause cycling issues. There is nothing wrong with your rifle! You should not alter your rifle just to make it shoot crappy, unreliable ammo. Steel cased ammo is not just cheap because it uses steel cases. That should not be a surprise to anyone who has used it before. |
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Alright, apparently there is some scaring under the gas block. I took the handguard off and lo and behold the whole block is loose. Also, it's missing one of the set screws on the gas block.
EDIT: The upper was from Mark's Armory. I contacted them and they are sending me new set screws with my gas block this afternoon. I'd rather not do this again, would loctite be appropriate on a gasblock or would another product be better for thermal considerations? Also, big thanks to Mark's for their customer service, these guys are awesome! |
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Quoted: All steel cased ammo ( except some hornady ) is under powered and will cause cycling issues. There is nothing wrong with your rifle! You should not alter your rifle just to make it shoot crappy, unreliable ammo. Steel cased ammo is not just cheap because it uses steel cases. That should not be a surprise to anyone who has used it before. I've shot thousands of rounds of Wolf steel case ammo. Never had any reliability issues so long as I kept the powder residue and varnish residue cleaned out. I haven't bought any Wolf in the past several years as now I'm either shooting M-855 or my reloads.  OP, glad you got it fixed. |
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