how tight should the AR-15 barrel be tightened?
- Thread starter imbane
- Start date
It actually depends on the year of manufacture for the rifle and who made it! The heavier touque value was used on the ealier guns while the torque specifications were relaxed for newer production!
Does that help? I don't have my book with me right now.
Scott
Does that help? I don't have my book with me right now.
Scott
Typically you tightenned it hand tight then go to the next barrel nut notch with a wrench, you will find that the next notch will be as far as it will go without ripping the vis off the bench and damaging the threads on the receiver.
Exactly what furet mentioned. Closest and hand tightest (one hand, no cheater bar). This technique has worked for my competition guns over the past 10 years, besides , I'm too old to deploy to Axxkrakistan, and if we did get over there, I can pick something up. 
In the meantime, go easy on that AR15 barrel collar with the wrench.
In the meantime, go easy on that AR15 barrel collar with the wrench.
I have never heard of this before. Where did this info come from?
As suggested in some of the comments, the reason for the big variance in torque spec is this; the nut must be tighted to a position where the gas tube will line up and pass through the nut. Tighten it initially to 30 ft pounds. See if the gas tube hole lines up. If not, tighten it until the hole lines up but do not exceed the upper torque level. If you are still shy of the hole lining up back off the nut and repeat the tihgtening. As you come up on torque you mate the threads and you can turn the nut further without going past the upper limit. You should always tighten and loosen 3 times whenever you are mating an upper or barrel nut that has never been mated to each other before. This ensures the threads are all touching each other and that way the thread fit will not loosen up.
-Bingo; as per Arwen Ace. I hadn't heard about old/new specs before, but I suppose that & different contractor's parts could make you need to vary your torque soemwhat?
The main reason I'm aware of for the big variance on torque specs is giving an upper & lower range that: 1) is tight enough to NOT come loose in use, and 2) is NOT so tight that you're risking damage to the aluminum upper receiver, or barrel nut.
Aligning the gas-tube into the upper receiver & carrier-key is the critical issue. If your gas tube can't clear your barrel-nut's teeth somewhere inside that torque-range, you have problems. I've worked on a few in & out of uniform, taught on them for a while, and I've never had any fail to align within the safe range.
The only thing I'd add is that I tend to flush clean both the receiver & nut threads before I start, wipe on some moly-disulphide grease onto both sets of threads, wipe most off (leaving an even thin coat), and once you've torqued the nut to alignment, undo it & repeat twice more.
The main reason I'm aware of for the big variance on torque specs is giving an upper & lower range that: 1) is tight enough to NOT come loose in use, and 2) is NOT so tight that you're risking damage to the aluminum upper receiver, or barrel nut.
Aligning the gas-tube into the upper receiver & carrier-key is the critical issue. If your gas tube can't clear your barrel-nut's teeth somewhere inside that torque-range, you have problems. I've worked on a few in & out of uniform, taught on them for a while, and I've never had any fail to align within the safe range.
The only thing I'd add is that I tend to flush clean both the receiver & nut threads before I start, wipe on some moly-disulphide grease onto both sets of threads, wipe most off (leaving an even thin coat), and once you've torqued the nut to alignment, undo it & repeat twice more.
