AR Sponsor
Posted: 8/1/2011 5:45:55 AM EDT
| My normal procedure for installing the barrel nut is to torque it to 35ft lbs and then tighten a bit more until everything lines up. Unfortunately on my current build, the nut pretty much lined up perfectly right at 35 ft lbs. I think if I try to go to the next notch it will be too tight. Is 35 ft lbs enough, or should I try and tighten it more? Thanks. |
|
75 seems really high to me. I thought you were supposed to keep it as close to 30ft/lbs as possible? When I built mine I torqued it to 30, then set my wrench to 40 and just lined it up (it didn't take much more movement, the wrench didn't even click out).
I am a noob though, so take everything I say with a grain of salt. |
|
Every combination of parts is a little different. Some will line up with torque over, but close to the 35 lb range. Some need to go up to, but not over 85 lbs. Some will fall in between. As long as it is in the torque range when your final nut groove is lined up with gas hole in the receiver, it is good.
So both of the above are correct. The one with 75 lbs., is on the higher end, but within spec and the one with close to 40 lbs. is on the low end, but within spec. ETA: High should be 80, not 85. Thanks Maryland Shooter. |
|
Quoted:
75 seems really high to me. I thought you were supposed to keep it as close to 30ft/lbs as possible? When I built mine I torqued it to 30, then set my wrench to 40 and just lined it up (it didn't take much more movement, the wrench didn't even click out). I am a noob though, so take everything I say with a grain of salt. I have assembled 5 uppers now and most of them weren't too far from 35lbs, but one of them took about 70lb to get it to line up. |
|
In order of builds:
1) 45 ft/lb - Lothar Walther barrel + Del-ton upper + Del-ton barrel nut 2) 78 ft/lb - Bushmaster barrel + Del-ton upper 3) 72 ft/lb - Green mountain barrel + De-ton upper + Del-ton barrel nut 4) 55 ft/lb - Colt barrel + Colt upper + Colt barrel nut 5) 63 ft/lb - FNMI barrel + Lars Grizzly upper + unknown barrel nut 6) 53 ft/lb - Colt barrel + Colt upper + Colt Barrel nut By no means am I saying a certain barrel nut, upper, and barrel combination produces higher torqued barrels, these are just my observations. The Lothar Walther barrel was easy to line up. The two colts I barrelled were by far the easiest to line up and were mid spec. The bushmaster and green mountain barrel were frustrating and hard to line up. The FNMI barrel was moderately easy to line up. On both the Colt barrels they were lined up at about 35 ft/lb but I opted to go to the next hole. The bushmaster barrel would line up at 28 ft/lb and then the next hole that lined up was over 70 ft/lb (weird). If i'm below 40 ft/lb I'll up to go to the next hole. |
|
Quoted:
Thanks. Loosening and re-torquing it a few times did the trick. It's lined up at 75 ft lbs now. Well you did it the hard way....you didn't have to go to all the way to 75. The reason you did it the hard way is because someone erroneously told you that the bottom of the range is 35 ft lbs. It is NOT 35 it is 30 !! Start looking for alignment as you approach 30...you would have been perfect at 35 ft lbs. This seems to happen all too frequently...it's 30 - 80 and start looking for alignment as you approach 30 ! DD This is easy. Oh, and this is WET TORQUE, use the correct lube like AeroShell 33MS. If you are doing this dry your torque values are meaningless. This is a steel barrel extension and an aluminum receiver. Don't volunteer for the higher end of the range (because of the obvious). |
|
Quoted:
I would have had to go to 75 anyway. After loosening it an re-torquing a couple times it was no longer lined up. At 35 ft lbs I was half way to the next notch, so it had to go tighter. I wouldn't call it f_cked up, just on the higher side of the range. If you had gone to 30 on the warm up, 35 might have been there for you on the final. At a point the steel threads start pulling the aluminum threads off the receiver so it's good to stay away from that threshold if you can. If you're within the range you're OK. DD Who fixed his verbage 
|
|
Go to 30...Line it up, and leave it alone. If it aligns at 30....So be it. It ain't going to back out on you since there is a gas tube holding it in place.
It has been said that the more you tighten it the more it affects accuracy...less is more if this is true. |
|
Quoted:
I would have had to go to 75 anyway. After loosening it an re-torquing a couple times it was no longer lined up. At 35 ft lbs I was half way to the next notch, so it had to go tighter. I wouldn't call it f_cked up, just on the higher side of the range. Your correct. |
AR Sponsor