How much torque on barrels

[carlsbad]

Is it OK to use anti seize - assuming the torque is 40-50 ft lbs?

OK (and recommended) to use antiseise of some sort no matter what the torque is.

 

[mr45man]

So I have heard differing things about how hard you should tighten a barrel. Some say 125lbs. And some of the bench shooters put them on with as low as 40 so they can change barrels at the range.

Now I have a friend who is a self taught gun smith. He turns on the barrel till it stops then puts a 8ft extension on the handle of his barrel wrench and turns it another 1/8 of a turn. Is this destroying the receiver? It's got to be more then 200 maybe even 500 lbs he is turning it to.

8’extension?would not let him near my gun.
Hand tight ,then with T handle wrench back off 1/4 turn and give it a snap into barrel. Done.

 

[jelenko]

Sorry for all the questions.

Is thread lube needed also if antiseize is used?

 

[Clark]

I can calculate the max torque for a screw or bolt. I can discount limited engagement. I got this from an engineer at Caterpillar posting on Practical Machinist gunsmith section.
I can discount for lubrication:
100% dry
75% oil or grease
50% wax.

I have over torqued and verified the failure predictions [calculating tension in fastener] in screws and bolts.

When I calculate torque for a rifle barrel, it is way over 1000 foot pounds. So you are not likely to strip the threads or snap the barrel off.

I did an experiment on minimum torque. In 2002 I put a Shilen bull barrel in .452" grooves on a Mauser in 45acp. Not SAAMI chamber, but 0.470" chamber. Very tight. I put a 40 X scope on it at the range and measured group size vs torque. I shot the same ~~ 3 moa all the way down to finger tight. I was shooting at 100 meters with 230 gr FMJ and ~ 40 kpsi [460 Rowland pressures].

 

[Grimstod]

This thread keeps on coming back from the dead.

 

[kneedtospeed]

Need to quit Lubing this thread, and just let it rust, er Rest....

 

[Clark]

Dusty StevensCOVFEFE-
↑
I found some additional information about this. That information states that they torque their barrels to 500 Ft Lbs.
That is rediculous. I wonder if he actually has a torque wrench?

If a guy weighs 200 pounds and leans hard on a 2.5' cheater bar, he can be confident he is close to 500 foot pounds of torque.

That is how I calculated it took 560 foot pounds to unscrew a WWII Mosin Nagant barrel.

 

[jelenko]

Dusty StevensCOVFEFE-
↑
I found some additional information about this. That information states that they torque their barrels to 500 Ft Lbs.
That is rediculous. I wonder if he actually has a torque wrench?

If a guy weighs 200 pounds and leans hard on a 2.5' cheater bar, he can be confident he is close to 500 foot pounds of torque.

That is how I calculated it took 560 foot pounds to unscrew a WWII Mosin Nagant barrel.

At 2.5 ft, you have to apply 224 lbs of force to get 560 ft lbs of torque. That means you hand, wrist, arm all 'holding' 224 lbs.

 

[tobnpr]

That means you hand, wrist, arm all 'holding' 224 lbs.

"Holding"? You set the receiver wrench at just over 90 degrees from the floor and push down with your body weight. Ain't no strength involved at all.

I've had some that needed all my 220 lbs on a 5' cheater pipe over the receiver wrench. Nothing like milsurps...'cept maybe a Tikka

 

[kneedtospeed]

 

[kneedtospeed]

 

[Grimstod]

Dusty StevensCOVFEFE-
↑
I found some additional information about this. That information states that they torque their barrels to 500 Ft Lbs.
That is rediculous. I wonder if he actually has a torque wrench?

If a guy weighs 200 pounds and leans hard on a 2.5' cheater bar, he can be confident he is close to 500 foot pounds of torque.

That is how I calculated it took 560 foot pounds to unscrew a WWII Mosin Nagant barrel.

It was a 6ft cheater bar.

 

[BoydAllen]

Sorry for all the questions.

Is thread lube needed also if antiseize is used?

no

 

[JayHHI6818]

Couldn’t resist

 

[jackieschmidt]

This thread keeps on coming back from the dead.

The reason it keeps coming back to life is self explanatory when you see a fellow shooter struggling with his new Benchrest Rifle, trying to get it to shoot better than .350 groups.
He brings the Rifle to you in hopes of finding something wrong. First, let’s take the barrel off. You place the barrel in your vice. Insert wrench. The barrel comes loose almost before you apply any pressure.

You tighten the barrel to the proper 70 to 80 pound feet, head to the range. The first group out of the Rifle is a “mid one”.

”But my gunsmith said just snap it against the shoulder”

yeh.

 

[Terry]

This is a 2014 post.

 

[jackieschmidt]

This is a 2014 post.

A lot of new shooters have come on the scene in six years. And judging from the questions ask as of late and the answers given, shooters are still ignorant of the concept of how a threaded joint works when the requirement is to hold two pieces firmly and truly together with no movement under normal use.

 

[jelenko]

This is a 2014 post.

So?

 

[DR_2297]

Barnard says 70 ft-lb and that is what I use on all 1.062-16 & 18 TPI threads. So far so good and you can disassemble without a gorilla - especially if using a thread lubricant at assy.

 

[Grimstod]

The reason it keeps coming back to life is self explanatory when you see a fellow shooter struggling with his new Benchrest Rifle, trying to get it to shoot better than .350 groups.
He brings the Rifle to you in hopes of finding something wrong. First, let’s take the barrel off. You place the barrel in your vice. Insert wrench. The barrel comes loose almost before you apply any pressure.

You tighten the barrel to the proper 70 to 80 pound feet, head to the range. The first group out of the Rifle is a “mid one”.

”But my gunsmith said just snap it against the shoulder”

yeh.

If the threads are crappy then yes.

Good threads you can snap them on with around 40lbs. There are very few gunsmiths out there that can make threads that good. I am not one of them.