barrel nut torque

[JackHass]

What torque setting are you guys using to tighten down the barrel nut on a Daniel Defense rail? Also on a Larue rail.....I'm having problems getting the larue to line up with the upper receiver.

Thanks in advance,
JH

[Hmac]

DD calls for 50-75 ft lbs on the Lite and RIS rails. I set my torque wrench to 70 ft lbs. I don't think it matters much.

[Robb Jensen]

Generally for DD Lite Rails (including RIS II and Omega X rails) I use 55-70ft lbs. LaRues usually require a lot of torque to get them to align, many times in excess of 80ft lbs. DD M4 rails I can usually align within spec of 35-80ft lbs without issue.

[JackHass]

I had to use 95 lbs to get the larue to align right. Isn't that way too much??

[Robb Jensen]

I had to use 95 lbs to get the larue to align right. Isn't that way too much??

I've had to torque that high before. It is above mil-spec, but then again mil-spec is for a steel barrel nut not an aluminum alloy one. If you grease it up well and torque, loosen, torque higher and loosen until you get there you won't cause any damage.

[Eric D.]

Aluminum threads are much more prone to wearing/stripping out with repeated torquing. Aluminum is one of the worst materials when it comes to failure from fatigue. I wouldn't even bother using a torque wrench. I would just snug it up and then bring the next hole into alignment. Depending on your barrel nut your "alignment" could require anywhere between 30 and 70 ft-lbs. Plus since aluminum expands twice as much as steel in./in./degree, you will end up with an interference fit when the barrel heats up. I would stay above 30 ft-lbs but not ever go over 70 ft-lbs. The LaRue keeper system locks down the barrel nut to prevent it from ever backing out anyway.

[EzGoingKev]

I had to use 95 lbs to get the larue to align right. Isn't that way too much??




I've had to torque that high before. It is above mil-spec, but then again mil-spec is for a steel barrel nut not an aluminum alloy one.

LaRue's barrel nut is steel.

I do mine by feel. I snug it down to about 50 ft lbs to seat the barrel and then tighten it again to about the same and then go more until it is lined up.

[Robb Jensen]

LaRue's barrel nut is steel.

Lost in translation.....

The Mil-Spec for torque is for the USGI style (read THIN) steel barrel nut. Some of the reason for the torque value is due to the damage to the barrel nut teeth you can do using a 3 pin USGI wrench the other reason is because you're torquing steel against aluminum.....which is why I said to grease it up well and slowly work the nut into mating with the upper receiver.

[Hmac]

LaRue's barrel nut is steel.

I do mine by feel. I snug it down to about 50 ft lbs to seat the barrel and then tighten it again to about the same and then go more until it is lined up.

Good plan for the Larue, but the DD Lite and RIS II rails don't have to be lined up for the gas tube. The ring spins freely even after the barrel nut is torques down. So, with those DD rails, you just pick your torque value and crank.

[Eric D.]

Good plan for the Larue, but the DD Lite and RIS II rails don't have to be lined up for the gas tube. The ring spins freely even after the barrel nut is torques down. So, with those DD rails, you just pick your torque value and crank.

I didn't know those DD rails don't have to line up for the gas tube :eek:. In that case, sure, just pick a number and go. While I would be inclined to use more torque for an aluminum barrel nut (Identical thermal expansion) I still wouldn't go over 70 ft-lbs.

[shadow65]

I torque my DD Lite to 50 ft. lbs.

[M4whore]

Make sure you adjust for torque if you have an offset adapter! I screwed up a barrel nut one time cause I was in a hurry. This is an easy link and a good double-check to use....

http://cncexpo.com/TorqueAdapter.aspx

[Brahmzy]

65-70 lbs. on my 3 DD Lite Rail nuts. Perfect.

Don't forget to torque, back, off, torque 4 times before final torque. You'll notice the nut WILL travel further with the same amount of torque applied each time...

[Eric D.]

Don't forget to torque, back, off, torque 4 times before final torque. You'll notice the nut WILL travel further with the same amount of torque applied each time...

This is because the material is being fatigued and pushed beyond its elastic limit. Do that a few more times on aluminum and the threads will be shot. This isn't really an accurate way to torque something to a certain value anyway. The purpose of torquing is to guarantee a certain force of friction between the threads; you can achieve this with one torquing.

I know this procedure may be the industry standard but I'm not convinced that it serves a positive purpose, especially on barrel nuts that need to line up for the gas tube.

[Dirtyboy333]

Sorry to post in this old thread but i did a search and figured it would be better than starting a new one.

Anyway, i took my upper and a torque wrench to my local smith because i didn't have the vice block. I told him to torque my DD lite barrel nut to 50 ft/lbs and i thought he did but when i got home i noticed the wrench was set at 70 ft/lbs which makes sense because the graduations on the wrench go from 55 straight to 70 ft/lbs. Also, the graduation marks are set up strangely and when its set on 70 its very easy to mistakenly think its at 55 ft/lbs. Additionally, while he was torquing the nut he mentioned that it felt heavier than 50.

So, while i see that some of you use 70 ft/lbs without problems i'm still a little concerned bc mine is torqued to 70 on the wrench but thats not including the extra leverage not accounted for from the DD adapter. I put a liberal amount of moly grease on the threads before taking it to him.

So, i have to return the wrench to Autozone. Do you think i should keep the wrench a little longer until i can make it back to the shop and have him loosen it or do you think everything will be fine. I recall some threads on here about over-torquing and the problems it can cause. I have all the parts for this gun and planned on putting it together tonight since its my last day off in a while but if it needs loosened i guess i'll have to wait to finish this project.

Thanks guys