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Posted: 9/26/2015 1:11:58 PM EDT
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I am trying to help a friend build an AR-15 for his son. We are at the point of attaching the barrel to the upper. Delta ring, weld spring and snap ring are assembled. I am placing the barrel in the upper and lining up the pin and slot. For some reason, I can not get the barrel nut to start. I try pushing in to compress the spring somewhat and I still can not get engagement. Any ideas on what I am doing wrong? Any and all help will be appreciated.
Thanks in advance. |
| We bought a used barrel assembly. I was hoping to find the problem without having to remove the sight base and take everything apart to get the spring, retainer and ring out of the way. May have to do that anyway. Barrel nut threads look good and the receiver threads are new. Should the weld spring have to be compressed to start the barrel nut or should it start easily? |
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I checked the barrel nut only. It appears that the barrel nut easily slips over the threads on the new upper. Now I understand why the nut won't start; the threads don't touch. The new upper threads mic at 1.240" outside to outside. Are there two sizes of barrel nuts? Upper was purchased from Brownell.
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| It's been a few years since I've played around with the 308 delta ring set up, but IIRC all of the 308 delta ring components are different than the AR15 ones. So if you do indeed have the 308 set up, you're going to have to order a new AR15 delta ring, weld spring and snap ring along with that new barrel nut. |
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