Barrel torque & accuracy

6

69beers

New member
Will anyone share their magic number for maximum accuracy when torquing down the barrel nut? My setup is a Lilja 20" barrel, LBC A3 upper, and a JP Vtac free float guard & barrel nut. Gas tube alignment isn't really an issue with this hand guard. Brownells tells you to keep it close to 35 ft/lbs for accuracy, JP states 50-80, and LBC said around 65 when I ordered the receiver. All of these numbers are after greasing the threads and tighten/loosen 3 times. This build will include truing the face of the receiver if needed and bedding with Loctite 242.

As you can see these torque numbers are all over the place. I've searched the history on here and other sites (this one being the most informative) and have read that too much or too little will degrade accuracy. Any ideas?

Thanks in advance!
 
I torque to 35 Ft/lbs and loosen 3 times, before tightening to align the gas tube hole. Final torque will usually end up btwn 40 and 55 ft/lbs by the time I get the gas tube holes lined up. After reaching 35 ft/lbs, final torque is really determined by when the holes line up. I've had no problems with accuracy doing this.
 
69beers,
In my many years of building these, 99% of the time, after hand tightening, the next hole where the gas tube goes in is at the proper poundage and will not go to the following one without cracking the receiver. Usually thats between the 35-60ft lbs. I beleive the 30ft lbs of torque is the minimum for the military standard.(i can be wrong, but i think thats what i remember from school)

So unfortunately, there is no magic number for torque.

Another note, if i rebarrel someones gun and find loctite on the barrel nut its an extra $40, don't do it!
 
I think he was talking about loctite on the barrel extension. The space between the extension and upper receiver hole. That's how I took it.
 
Scott, I have heard people do that and call it bedding the barrel or something. I had just recently heard of it in another post, and was curious if that really did much.
 
I don't mean to be critical and maybe some folks do it, but ive never heard of it until now and was wondering the purpose. Some upper receivers do fit the barrel looser than others, maybe thats the reasoning.

Theres one thing I learned a long time ago, do what you want to your gun that makes you more confident.
 
I wonder if blue loctite would hold up to the heat the chamber could potentially produce? Seem like it could get hot, run out and cause other issues. One day when I was pardon the term (Commey Blasting) with my M44 I had all the red loctite melt and leak out. I had it holding the mount for my forward mounted scout scope on to the rear sight block.
 
Bedding the barrel extension with blue loctite is a tip I got from Mike at Dtech. To be honest I never thought about how it holds up to extreme heat, my guess would be no better than the red that you experienced melting out. But it's not a problem for the way I usually shoot.
 
Originally Posted By: 204 ARBedding the barrel extension with blue loctite is a tip I got from Mike at Dtech. To be honest I never thought about how it holds up to extreme heat, my guess would be no better than the red that you experienced melting out. But it's not a problem for the way I usually shoot.

The only place I might have an issue with it gettting hot in on a PD shoot. I agree that most of us don't get them that hot, at least not very often. The .204 barrel I just got was so tight that I was afraid I wouldn't get it in the receiver. If I would have tried to use loctite on it, I wouldn't have got it together I'm pretty sure. I could see where it would work pretty good if it was loose fit in the receiver like the 20" 6x45 P3 barrel my buddy got.
 
Yeah, I agree with you that it may not be necessary most of the time. But with a loose one like you mentioned it couldn't hurt anything. It's just another way to try to "even out" the tolerance variations.
 
While I understand the concept of using locktite on the barrel extension, I don't think I'd want it done on a rifle of mine. I was taught to use anti sieze on that surface. Maybe I'd need to remove the barrel sometime.
 
Originally Posted By: coyote6974While I understand the concept of using locktite on the barrel extension, I don't think I'd want it done on a rifle of mine. I was taught to use anti sieze on that surface. Maybe I'd need to remove the barrel sometime.

Valid concern, but the barrel is still easily removable, without the use of heat or anything else. I've had to do that myself.
 


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