AR Sponsor
Posted: 10/30/2013 7:56:12 PM EDT
|
I am working on a new 308 build. LR308 upper with factory barrel nut, rainier select barrel. When installing the barrel nut it gets caught on the first raised portion of the chamber on the barrel. I've tried grease with moderate persuasion. Is this normal should I contact Rainier? Should I try and lightly remove some barrel finish?
Thanks for any advice. TJ |
|
Sounds like to me the barrel nut is under sized or the barrel chamber area is over sized. Take some measurements and call Rainier and while you are at it, call DPMS to confirm the proper ID of the LR-308 barrel nut. One of the two is possibly out of spec if it will not slide past the chamber on the barrel. Regardless of whether or not it is an AR10 or LR-308 barrel nut it should slip over the barrel all the way down to the barrel extension. It may be a simple fix such as taking a few thousandths off the ID of the barrel nut because of tolerance stacking. Take some 200 grit wet-dry and wrap it around your finger and do some polishing around the ID of the barrel nut taking care to remove metal equally around the opening. Do this only after ruling out either the barrel nut or barrel being out of spec. A .001 or .005 inch in that area is not going to hurt anything but if more than that then something else needs to be done, either replace the barrel nut or Rainier should turn the barrel down.
|
|
Quoted:
Sounds like to me the barrel nut is under sized or the barrel chamber area is over sized. Take some measurements and call Rainier and while you are at it, call DPMS to confirm the proper ID of the LR-308 barrel nut. One of the two is possibly out of spec if it will not slide past the chamber on the barrel. Regardless of whether or not it is an AR10 or LR-308 barrel nut it should slip over the barrel all the way down to the barrel extension. It may be a simple fix such as taking a few thousandths off the ID of the barrel nut because of tolerance stacking. Take some 200 grit wet-dry and wrap it around your finger and do some polishing around the ID of the barrel nut taking care to remove metal equally around the opening. Do this only after ruling out either the barrel nut or barrel being out of spec. A .001 or .005 inch in that area is not going to hurt anything but if more than that then something else needs to be done, either replace the barrel nut or Rainier should turn the barrel down. Yes. Im using the LR-308 upper and the LR-308 hand guard barrel nut works on both the parts with out the barrel. It is the barrel nut that came with the handguard. Pictured here http://www.jsesurplus.com/dpms308sasshandguard-riflelength.aspx Ill call rainier today. |
|
Seems to me that I used a regular AR15 barrel nut on both of my Mega10 builds. I just checked a WOA 5.56 barrel, it's 1.000 where the barrel nut goes, and I'm using a standard barrel nut there.
I'd bank on it that there's nothing wrong with your barrel from Rainiers. They sell quality barrels. I'd say the problem is your barrel nut! 
Edit: I see it's a DPMS barrel nut. Bet that is your proublem |
DPMS bashing, boy, that was helpful. Just couldn't wait to throw that out there could you?
The DPMS LR upper receiver does NOT use AR barrel nuts. Don't even try to tell him it might. Did you measure the OD of the barrel and the ID of the barrel nut yet? If it is within .005 difference or so just buff down the ID of the barrel nut. Do not touch the barrel. The old rule of thumb applies here, always alter the least expensive part. I had something similar happen on a custom LR barrel and aftermarket forend where after coating the OD of the barrel was just a bit snug on the forend lockup plate. NOT a DPMS product either but a very respected top tier aftermarket forend maker! A little buffing on the ID of the lock up plate until it slipped over the barrel and all was well. |
|
I'll second that - this has been a problem for a few folks with other barrel nuts too. Seems like the fix was to take a little emery cloth or such and slightly enlarge the ID of the barrel nut. It's not so much a case of something being out of spec so much as tolerance stacking. |
|
Quoted:
DPMS bashing, boy, that was helpful. Just couldn't wait to throw that out there could you?
The DPMS LR upper receiver does NOT use AR barrel nuts. Don't even try to tell him it might. Did you measure the OD of the barrel and the ID of the barrel nut yet? If it is within .005 difference or so just buff down the ID of the barrel nut. Do not touch the barrel. The old rule of thumb applies here, always alter the least expensive part. I had something similar happen on a custom LR barrel and aftermarket forend where after coating the OD of the barrel was just a bit snug on the forend lockup plate. NOT a DPMS product either but a very respected top tier aftermarket forend maker! A little buffing on the ID of the lock up plate until it slipped over the barrel and all was well. DPMS bashing, boy, that was helpful. Just couldn't wait to throw that out there could you? Not sure where in the hell you came up with that. I happen to own a highly modified DPMS Oracle, that is one of my favorite rifles to shoot. What I was saying that I doubted that the Rainier barrel was the problem. More than likely the Barrel nut which happens to be a DPMS. I had no idea what a LR 308 was till I looked it up. The fore end kind of looks like a Jp, but I don't know. My DPMS uses a standard barrel nut. I don't have any beef with DPMS. I'd never buy their 5.56,because of bad reviews over the years, but I sure like their .308 Sorry but it seemed logical to figure that the Rainier barrel was "Good to Go" and the barrel nut was the problem. You can climb down from that horse now. 
|
AR Sponsor