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Posted: 12/26/2016 8:08:17 PM EDT
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I bought a lightly used Spike's upper,installed a new Spike's barrel with a YHM handguard.I used a New PSA premium BCG.My problem is that the bolt will not rotate and lock into the barrel extension.It will ALMOST go....
I tried another new BCG from AIM, and it won't lock either.When I tried these same bolts in another new upper they both locked in place as they should. I took the Spike's barrel off the upper and couldn't visually see any problem. if I don't torque the barrel nut---just pull it up snug---either BCG will work........,. I've assembled a few dozen uppers and never had this problem. Advice appreciated! |
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Well I have rather limited experience barreling uppers, only three or four. But if you can't get a bolt to lock up with the barrel not installed then it sounds like an out of spec barrel extension. Especially since the same bolts will lock up in other guns. Thats what I think too. |
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Here's a thread for reference. I'm not saying you're having the same issue but it's something to look at.
http://www.ar15.com/forums/t_3_4/706604_Bolt-won-t-close-on-new-build----.html |
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He didn't say anything about trying without the barrel in the upper just with a loose barrel nut. Even if that barrel nut were to be handtight he should be able to cycle the BCG. He tried two different BCGs' and for that reason alone I would send that barrel back. |
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Is it binding on the gas tube? Look down into the inside of the upper. Gas tube centered?
Does the bcg move freely in the upper with the bolt out of it? If it's none of that, probably the barrel. Will say... Those bcgs are junk. Also helps avoid size issues and tolerance attacking to use parts of the same manufacturer. At least I'd do the same make for barrel, upper, and bcg; at a minimum. |
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Even if that barrel nut were to be handtight he should be able to cycle the BCG. He tried two different BCGs' and for that reason alone I would send that barrel back. Go to the thread I linked above. It's not about the tension from the nut rather the barrel may be rotating slightly. With the nut loose the barrel can be jarred back to the position(chamfered edges) where the lugs on the bolt and extension line up properly allowing the bolt to go into battery. Again I'm not saying it's the problem just a possibility. |
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Call Spikes and tell them the barrel extension is out of spec. They will give you a return for the one you have and either fix it or send you a new one. Spikes has always been good. This is the right advice. I don't know that the barrel-extension is out of spec but that would be my suspicion. Explain to them what is going on and ask what you should do. They have some of the best CS around and they will take good care of you. Good luck with getting it up and running soon... |
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Go to the thread I linked above. It's not about the tension from the nut rather the barrel may be rotating slightly. With the nut loose the barrel can be jarred back to the position(chamfered edges) where the lugs on the bolt and extension line up properly allowing the bolt to go into battery. Again I'm not saying it's the problem just a possibility. I think that barrel extension is out of spec. You could be right but either way I don't think its safe to shoot. Edit: If it is the barrel moving, I'd order barrel nut shim (they are $5.00) http://bisonarmory.com/ar-15-barrel-nut-shim-set/ I would give it another try it again cycling the BCG and check headspace. If that does not work, its the barrel extension out of spec. |
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OP, a picture is worth a thousand words. Can you remove the barrel nut, leaving the barrel in place, and show us a picture of the barrel extension flange seated against the upper face and the barrel pin in the slot? I'd like to make sure it is fully seated in the upper with the pin in its proper place.
Then, a picture taken from the bottom side of the upper displaying the position of the barrel extension in the receiver. BCG completely removed, barrel still in place. Those two pics would really be helpful. |
| The locking lugs are too close to the breech face. Either the end of the barrel is machined wrong or the barrel extension is. Try it by hand to see if that's right; take the bolt out of the carrier, stick it in the extension and see if it will turn. It probably is hitting the breech face early and the rear of the lugs cannot clear the locking lugs. Everything is working properly to prevent you from chambering a round in this faulty set-up. |
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