User Panel
Posted: 8/19/2014 6:14:02 PM EDT
Ya'll were so helpful with my first question ("Have I Ruined My Barrel") that I thought I would post another.
I replaced my badly drilled barrel, thanks to the brother-in-law. However, after properly drilling the sight base this time, when I went to torque the new barrel to the upper receiver I ran into a problem. Torqued at 30 lbs it ended up with a "tooth" of the milspec barrel nut grooves smack-dab in the middle of the hole for the gas tube in the upper receiver . The problem? Advancing the barrel nut to the next gas tube slot would exceed 80 lbs of torque and I did not wish to strip the threads on the receiver. So, will a new, perhaps better, barrel nut help? Are shims a possibility? If so, do the shims go in front of the shoulder on the barrel where it goes into the receiver, or behind it? If between the barrel shoulder and the receiver, will this affect headspace? Ideas that have worked for you? |
|
[#1]
Lube the barrel nut good and do repeated tightening/loosening.
|
|
[#2]
|
|
[#3]
Call up Spikes Tactical (or IM Tom) and ask them if you can get cheap shipping on a set of barrel nut shims. Once you get them, try one of the thin shims and see if that does the trick.
I use these A LOT in my builds. EVERY single MI rail I have bought (SS and TT series) have required them to get about 40-50lbs. If not for the shims it would have taken over 80ft to get the notches aligned. |
|
[#4]
I ran into this with a couple of aero uppers. It turned out that there was a minor amount of flashing on the leading edge of the threaded section. A few passes on an 8000 grit water stone and they were perfect. It never even went through the anodizing, just removed a small ridge. Worked for me.
|
|
[#5]
10 pack for $10... http://www.ebay.com/itm/223-Free-Float-Quad-Rail-Barrel-Nut-Shim-Barrel-Nut-Washers-10-Pack-/181406812780?pt=LH_DefaultDomain_0&hash=item2a3cb04a6c
3 pack for $4.55 http://www.ebay.com/itm/223-Free-Float-Quad-Rail-Barrel-Nut-Shim-Barrel-Nut-Washers-3-Pack-/181395895239?pt=LH_DefaultDomain_0&hash=item2a3c09b3c7 |
|
[#6]
|
|
[#7]
Quoted:
The threads will seat into each other, closely matched. This will get the parts close enough to line up the barrel nut within the torque spec. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Lube the barrel nut good and do repeated tightening/loosening. The threads will seat into each other, closely matched. This will get the parts close enough to line up the barrel nut within the torque spec. Nope, didn't happen. At 30 lbs the next usable groove would have been well over 80 lbs. The barrel nut worked fine on the previous barrel (same brand and specs) but not on the new barrel. |
|
[#8]
Quoted:
I ran into this with a couple of aero uppers. It turned out that there was a minor amount of flashing on the leading edge of the threaded section. A few passes on an 8000 grit water stone and they were perfect. It never even went through the anodizing, just removed a small ridge. Worked for me. View Quote I will take a look at this. My water stones are sitting dry in the garage, but water is free. I looked at a video on youtube about lapping the face of the barrel receiver on the upper using a tool from Brownells and lapping compound. This sounds cheaper and easier. |
|
[#9]
Quoted:
10 pack for $10... http://www.ebay.com/itm/223-Free-Float-Quad-Rail-Barrel-Nut-Shim-Barrel-Nut-Washers-10-Pack-/181406812780?pt=LH_DefaultDomain_0&hash=item2a3cb04a6c 3 pack for $4.55 http://www.ebay.com/itm/223-Free-Float-Quad-Rail-Barrel-Nut-Shim-Barrel-Nut-Washers-3-Pack-/181395895239?pt=LH_DefaultDomain_0&hash=item2a3c09b3c7 View Quote Thanks for the link on the shims. My build is not a free float -- just plain old mil spec carbine with a delta ring assembly/barrel nut. I couldn't find the inside diameter for the shims. Do they fit an ordinary milspec barrel at the receiver? And do they go in front of the barrel shoulder or behind it? |
|
[#10]
Quoted:
Call up Spikes Tactical (or IM Tom) and ask them if you can get cheap shipping on a set of barrel nut shims. Once you get them, try one of the thin shims and see if that does the trick. I use these A LOT in my builds. EVERY single MI rail I have bought (SS and TT series) have required them to get about 40-50lbs. If not for the shims it would have taken over 80ft to get the notches aligned. View Quote I am not using a Midwest Industries rail, just a plain Jane milspec carbine with a delta ring assembly/barrel nut and Magpul MOE furniture. Will shims work for that application? |
|
[#11]
No shims.
Tighten to 30+, loosen, tighten to 30+, loosen, on the 3rd & final time, take it all the way. You'll get it. Worst case scenario: buy a new nut, they're cheap, but you really really really shouldn't have to. |
|
[#12]
If the tooth is dead middle the barrel nut should be able to tighten up to the next notch way before 80lbs. Did you set your wrench to 80 and then do the final torque or are you stopping at 30 and then trying to tighten it up. If so you may want to try setting to 50lbs and work your way up.
I guess if all the parts are used they may have "stretched" a little and a new barrel nut might not be a bad idea. As for the shims they go in front of the shoulder right in between the barrel and the barrel nut and will be the same diameter as the "shoulder" on the barrel. |
|
[#13]
Quoted:
No shims. Tighten to 30+, loosen, tighten to 30+, loosen, on the 3rd & final time, take it all the way. You'll get it. Worst case scenario: buy a new nut, they're cheap, but you really really really shouldn't have to. View Quote This^^ They are cheap, and good to have a few extra around. If one doesn't torque the way you like it, use a different one. It's luck of the draw as to where they align when torqued, so you might use the rejected nut on the next build and be just fine. |
|
[#14]
Quoted:
I am not using a Midwest Industries rail, just a plain Jane milspec carbine with a delta ring assembly/barrel nut and Magpul MOE furniture. Will shims work for that application? View Quote View All Quotes View All Quotes Quoted:
Quoted:
Call up Spikes Tactical (or IM Tom) and ask them if you can get cheap shipping on a set of barrel nut shims. Once you get them, try one of the thin shims and see if that does the trick. I use these A LOT in my builds. EVERY single MI rail I have bought (SS and TT series) have required them to get about 40-50lbs. If not for the shims it would have taken over 80ft to get the notches aligned. I am not using a Midwest Industries rail, just a plain Jane milspec carbine with a delta ring assembly/barrel nut and Magpul MOE furniture. Will shims work for that application? Yes, they will work with a regular barrel nut just fine. Don't know about the Ebay ones, but I know the Spike's are good to go. |
|
[#15]
Another option that has other benefits is to lap the face of the receiver. I do this to all my uppers. It trues the interface between the barrel extension flange and the face of the upper. Anybody shooting benchrest doesn this to all theirs already. The slight amount of material removed though can give you that extra few degrees you need to torque the nut.
If that doesn't get you all the way to where you need to be there is nothing wrong with using a shim or 2. The thickness is so thin they reall do only accound fora partial turn of the nut, no harm no foul. |
|
[#16]
Bison Armory barrel shims, they even have a vid on the website for us more mechanically challenged.
|
|
[#17]
Quoted:
No shims. Tighten to 30+, loosen, tighten to 30+, loosen, on the 3rd & final time, take it all the way. You'll get it. Worst case scenario: buy a new nut, they're cheap, but you really really really shouldn't have to. View Quote This. I believe Colt and BCM, just gorilla grip their nuts until hell or high water. I've accidentally put WAAAAAY more torque than anyone ever should on an upper before and the threads weren't even galled. It isn't best practice to overtighten, but I bet we'd be surprised at some manf tightening specs on barrel nuts that require indexing. I guarntee they err on the side of overtightening and not shimming or undertorquing. |
|
[#18]
Quoted:
No shims. Tighten to 30+, loosen, tighten to 30+, loosen, on the 3rd & final time, take it all the way. You'll get it. Worst case scenario: buy a new nut, they're cheap, but you really really really shouldn't have to. View Quote Did all that. No go. Advice about a new nut seems a good idea. |
|
[#19]
Quoted:
If the tooth is dead middle the barrel nut should be able to tighten up to the next notch way before 80lbs. Did you set your wrench to 80 and then do the final torque or are you stopping at 30 and then trying to tighten it up. If so you may want to try setting to 50lbs and work your way up. I guess if all the parts are used they may have "stretched" a little and a new barrel nut might not be a bad idea. As for the shims they go in front of the shoulder right in between the barrel and the barrel nut and will be the same diameter as the "shoulder" on the barrel. View Quote I wondered if the thin metal and thread of the nut could have stretched. Thanks for the advice on where to put the shim. |
|
[#20]
Quoted:
Yes, they will work with a regular barrel nut just fine. Don't know about the Ebay ones, but I know the Spike's are good to go. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
Call up Spikes Tactical (or IM Tom) and ask them if you can get cheap shipping on a set of barrel nut shims. Once you get them, try one of the thin shims and see if that does the trick. I use these A LOT in my builds. EVERY single MI rail I have bought (SS and TT series) have required them to get about 40-50lbs. If not for the shims it would have taken over 80ft to get the notches aligned. I am not using a Midwest Industries rail, just a plain Jane milspec carbine with a delta ring assembly/barrel nut and Magpul MOE furniture. Will shims work for that application? Yes, they will work with a regular barrel nut just fine. Don't know about the Ebay ones, but I know the Spike's are good to go. Thanks. Very helpful. |
|
[#21]
Quoted:
This. I believe Colt and BCM, just gorilla grip their nuts until hell or high water. I've accidentally put WAAAAAY more torque than anyone ever should on an upper before and the threads weren't even galled. It isn't best practice to overtighten, but I bet we'd be surprised at some manf tightening specs on barrel nuts that require indexing. I guarntee they err on the side of overtightening and not shimming or undertorquing. View Quote View All Quotes View All Quotes Quoted:
Quoted:
No shims. Tighten to 30+, loosen, tighten to 30+, loosen, on the 3rd & final time, take it all the way. You'll get it. Worst case scenario: buy a new nut, they're cheap, but you really really really shouldn't have to. This. I believe Colt and BCM, just gorilla grip their nuts until hell or high water. I've accidentally put WAAAAAY more torque than anyone ever should on an upper before and the threads weren't even galled. It isn't best practice to overtighten, but I bet we'd be surprised at some manf tightening specs on barrel nuts that require indexing. I guarntee they err on the side of overtightening and not shimming or undertorquing. Right now it is under-torqued (about 20-25 lbs) to make it line up. Not comfortable with that. But if I over-torque I would probably be the one to strip the threads! Too cautious to try it. |
|
[#22]
Quoted:
Bison Armory barrel shims, they even have a vid on the website for us more mechanically challenged. View Quote Thanks for the source. They have a video, but the guy puts the shim behind the barrel shoulder -- between the barrel and the face of the receiver. I wondered if that would affect headspace. |
|
[#23]
Quoted:
Another option that has other benefits is to lap the face of the receiver. I do this to all my uppers. It trues the interface between the barrel extension flange and the face of the upper. Anybody shooting benchrest doesn this to all theirs already. The slight amount of material removed though can give you that extra few degrees you need to torque the nut. If that doesn't get you all the way to where you need to be there is nothing wrong with using a shim or 2. The thickness is so thin they reall do only accound fora partial turn of the nut, no harm no foul. View Quote Thanks. Good advice. |
|
[#24]
Quoted:
Yes, they will work with a regular barrel nut just fine. Don't know about the Ebay ones, but I know the Spike's are good to go. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
Call up Spikes Tactical (or IM Tom) and ask them if you can get cheap shipping on a set of barrel nut shims. Once you get them, try one of the thin shims and see if that does the trick. I use these A LOT in my builds. EVERY single MI rail I have bought (SS and TT series) have required them to get about 40-50lbs. If not for the shims it would have taken over 80ft to get the notches aligned. I am not using a Midwest Industries rail, just a plain Jane milspec carbine with a delta ring assembly/barrel nut and Magpul MOE furniture. Will shims work for that application? Yes, they will work with a regular barrel nut just fine. Don't know about the Ebay ones, but I know the Spike's are good to go. Thanks. If I go this route I'll give Spike's a call. |
|
[#25]
Quoted:
If the tooth is dead middle the barrel nut should be able to tighten up to the next notch way before 80lbs. Did you set your wrench to 80 and then do the final torque or are you stopping at 30 and then trying to tighten it up. If so you may want to try setting to 50lbs and work your way up. . . . . View Quote We increased the poundage on the torque wrench until it reached 80 lbs. I did not want to push it further. |
|
[#26]
Get a couple of extra barrel nuts to try. I would also recommend lapping the face of the receiver. If the tooth is in the center, I bet you you can get it moved over to the right spot. Forget the torque reading, once you hit minimum that really is all that matters. Put some muscle into it and use a breaker bar.
|
|
[#27]
Quoted:
Right now it is under-torqued (about 20-25 lbs) to make it line up. Not comfortable with that. But if I over-torque I would probably be the one to strip the threads! Too cautious to try it. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
No shims. Tighten to 30+, loosen, tighten to 30+, loosen, on the 3rd & final time, take it all the way. You'll get it. Worst case scenario: buy a new nut, they're cheap, but you really really really shouldn't have to. This. I believe Colt and BCM, just gorilla grip their nuts until hell or high water. I've accidentally put WAAAAAY more torque than anyone ever should on an upper before and the threads weren't even galled. It isn't best practice to overtighten, but I bet we'd be surprised at some manf tightening specs on barrel nuts that require indexing. I guarntee they err on the side of overtightening and not shimming or undertorquing. Right now it is under-torqued (about 20-25 lbs) to make it line up. Not comfortable with that. But if I over-torque I would probably be the one to strip the threads! Too cautious to try it. You wont strip the threads, I promise you. You might strip the teeth on the barrel nut, but not a big deal if you have an extra. |
|
[#28]
|
|
[#29]
Quoted:
We increased the poundage on the torque wrench until it reached 80 lbs. I did not want to push it further. View Quote View All Quotes View All Quotes Quoted:
Quoted:
If the tooth is dead middle the barrel nut should be able to tighten up to the next notch way before 80lbs. Did you set your wrench to 80 and then do the final torque or are you stopping at 30 and then trying to tighten it up. If so you may want to try setting to 50lbs and work your way up. . . . . We increased the poundage on the torque wrench until it reached 80 lbs. I did not want to push it further. Just for clarity. Did you tighten at 80lbs with the nut loosened or was it already torqued to 30 and then bumped up. |
|
[#30]
I bought a Seekins rail and it came with 3 shims. I ended up using 2 of them.
|
|
[#31]
Quoted:
Just for clarity. Did you tighten at 80lbs with the nut loosened or was it already torqued to 30 and then bumped up. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
If the tooth is dead middle the barrel nut should be able to tighten up to the next notch way before 80lbs. Did you set your wrench to 80 and then do the final torque or are you stopping at 30 and then trying to tighten it up. If so you may want to try setting to 50lbs and work your way up. . . . . We increased the poundage on the torque wrench until it reached 80 lbs. I did not want to push it further. Just for clarity. Did you tighten at 80lbs with the nut loosened or was it already torqued to 30 and then bumped up. We torqued, then bumped up |
|
[#32]
View Quote Thanks. Helpful article |
|
[#33]
Quoted:
Quoted:
Quoted:
Quoted:
If the tooth is dead middle the barrel nut should be able to tighten up to the next notch way before 80lbs. Did you set your wrench to 80 and then do the final torque or are you stopping at 30 and then trying to tighten it up. If so you may want to try setting to 50lbs and work your way up. . . . . We increased the poundage on the torque wrench until it reached 80 lbs. I did not want to push it further. Just for clarity. Did you tighten at 80lbs with the nut loosened or was it already torqued to 30 and then bumped up. We torqued, then bumped up May want to try starting at 60 or 70 and see if that gives you any movement. Also degrease all surfaces and re-lube as you may have some small particles causing it to bind. If 60 or 70 gives some movement but is still shy re-loosen and try at 80. |
|
[#34]
If you can't get a notch to line up at no more than 80 ft/lb, then something is wrong. Maybe the face of the upper is off or has excessive anodizing built up on it. Maybe the barrel flange isn't perfect. And maybe the barrel nut isn't doing its part. Since shims often cost at least as much as a barrel nut, I'd go with a new barrel nut first.
The torque spec is based on a standard GI upper, standard GI barrel and standard GI barrel nut, using the GI specified grease on the threads of the upper and nut. The characteristics of the grease can make a difference. I didn't see anything about what kind of grease you were using, if any. You GOTTA have a grease that is at least similar to the GI spec grease, or worrying about the torque is irrelevant. Another issue may be that you stopped at 30 ft/lb and then tried to bump it up to align the nut. Try backing off again and torquing from the beginning with the wrench set to something like 75 ft/lb. It does make a difference. |
|
[#35]
If it is just a HAIR too far at 30lb, it will always be well over 80lbs to get it to line up at the next groove. That's expected. You can either swap barrel nuts, face the receiver, use shims, or just do what I and most everyone else does.
Use a breaker bar, grease the threads with the correct grease, and torque that nut TIGHT about 10 times. Then run it back on with a torque wrench. If 80 lbs gets you real close, just finish it with a breaker bar and forget about it. I have used 90 to 100lbs on a ton of them and that's just fine. But if you don't want to do this, just keep re-torqueing and it WILL come in no matter what you say. |
|
[#36]
Quoted:
Thanks for the source. They have a video, but the guy puts the shim behind the barrel shoulder -- between the barrel and the face of the receiver. I wondered if that would affect headspace. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Bison Armory barrel shims, they even have a vid on the website for us more mechanically challenged. Thanks for the source. They have a video, but the guy puts the shim behind the barrel shoulder -- between the barrel and the face of the receiver. I wondered if that would affect headspace. Headspace is determined by the bolt locking into the barrel extension. It'll be correct no matter where you stick the shims. Posted Via AR15.Com Mobile |
|
[#37]
Very helpful information, everyone. Headed to the Fort Worth gun show on Saturday. i'll pick up a few more barrel nuts and give it a try. I'll also look for the mil spec grease -- I used white lithium. Cleaned that off after a while and use copper based antiseize. if the new nut doesn't get me there I'll implement the other suggestions. Thanks for the help.
|
|
[#38]
Quoted:
Headspace is determined by the bolt locking into the barrel extension. It'll be correct no matter where you stick the shims. Posted Via AR15.Com Mobile View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
Bison Armory barrel shims, they even have a vid on the website for us more mechanically challenged. Thanks for the source. They have a video, but the guy puts the shim behind the barrel shoulder -- between the barrel and the face of the receiver. I wondered if that would affect headspace. Headspace is determined by the bolt locking into the barrel extension. It'll be correct no matter where you stick the shims. Posted Via AR15.Com Mobile Good to know. |
|
[#39]
Quoted:
If you can't get a notch to line up at no more than 80 ft/lb, then something is wrong. Maybe the face of the upper is off or has excessive anodizing built up on it. Maybe the barrel flange isn't perfect. And maybe the barrel nut isn't doing its part. Since shims often cost at least as much as a barrel nut, I'd go with a new barrel nut first. The torque spec is based on a standard GI upper, standard GI barrel and standard GI barrel nut, using the GI specified grease on the threads of the upper and nut. The characteristics of the grease can make a difference. I didn't see anything about what kind of grease you were using, if any. You GOTTA have a grease that is at least similar to the GI spec grease, or worrying about the torque is irrelevant. Another issue may be that you stopped at 30 ft/lb and then tried to bump it up to align the nut. Try backing off again and torquing from the beginning with the wrench set to something like 75 ft/lb. It does make a difference. View Quote I'll give 'er another try. The nut worked fine on the first barrel with zero issues. This replacement barrel is another story. |
|
[#40]
Quoted:
If it is just a HAIR too far at 30lb, it will always be well over 80lbs to get it to line up at the next groove. That's expected. You can either swap barrel nuts, face the receiver, use shims, or just do what I and most everyone else does. Use a breaker bar, grease the threads with the correct grease, and torque that nut TIGHT about 10 times. Then run it back on with a torque wrench. If 80 lbs gets you real close, just finish it with a breaker bar and forget about it. I have used 90 to 100lbs on a ton of them and that's just fine. But if you don't want to do this, just keep re-torqueing and it WILL come in no matter what you say. View Quote Just wanted to say "Thanks" for this. I was having the same problem as the OP yesterday with my first build and found this thread. It was a hair too far at 30 Ft/Lbs and didn't quite make it to the notch at 80 Ft/Lbs. I followed your advice...using Aeroshell and torqueing that not tight 10 times or so. It got me closer...but after that..it ended up being 96 Ft/Lbs to line up. I started at 80 and just kept bumping it up about 2 Ft/Lbs per attempt until I hit about 98...then I'd back it all the way back off and start again. Eventually it settled at 94-96 Ft./Lbs and I called it good. Thank you. |
|
[#41]
To add a tiny bit to FALARAK's post, the spec of 80 ft/lb is not a "hard limit" that exceeding will cause sudden and immediate damage or some such nonsense. It's purpose is to preserve as much serviceability in a GI upper as possible, and it's based on and expectation of a military armorer's bench stock full of barrel nuts to play with in case they can't get the nut they're using aligned. If you need a long breaker bar and two helpers to get the next notch aligned, there's a problem, but don't get so hung up on that "80 ft/lb" spec.
|
|
[#42]
Follow up and final solution:
I picked up a few barrel nuts (as quite a few suggested) at the Fort Worth gun show, as well as shims. The first new barrel nut I tried solved the issue. Perfect alignment. Mounted the Vortex SPARC II today. The rifle is finished. I will sight it in on Sunday. Already thinking about the next build. Thanks for all the help. |
|
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.