Torque on barrel to action?

[nekshot]

What is the least amount of torque a barrel needs and why? I always heard 75 lbs and I have been thinking (this gets me in trouble) how neat it would be to dedicate a number of barrels to one specific action only. The sights to realign are no issue(there are none) and if all were indexed to a certain mark headspace should always be the same, I think. (my thinking can be negative) So, I trust you fellas will instruct and inform me on this issue.Thanks,nekshot

[B R Shooter]

Assuming you're talking rifles here, switch barrel guns are not uncommon. With a properly machined barrel and trued action, you can hav as many barrels set up for one action as you wish. Lots of opinions about torque, but 75 to 100 pounds aren't excessive. Again, when the two surfaces match, when they contact, there isn't much movement. Fer Gods sake though, lube the threads and the barrel shoulder!

[felix]

35 pounds on a BR class (everything squared to a tee) gun is fine. ... felix

[B R Shooter]

35 pounds on a BR class (everything squared to a tee) gun is fine. ... felix

This horse has been beaten pretty hard already. I think you need to ask some of the top BR smiths in the Country if 35 pounds is enough.

[nekshot]

Thanks fellas and I don't want to beat a dead horse but I have used less than 75 and everything works fine but I feel a little guilty about it. I know alot is grandma taught it and we bought it. I simply wanted to sooth my soul and trust what I have done is ok(so far so good) and what I want to do in future project will be ok. In my limited background experience if you have to crush threads to get a finnished product on any thing some thing was not machined to fit properly.

[MBTcustom]

I was taken to school on this very issue by a high-end rifle builder who is also a member here. He told me to quit torquing the snot out of my barrels because it is completely unnecessary.
He told me to cut the threads in the barrel, and chamber the barrel in the lathe, then screw the action on the barrel hand tight.
Then insert the bolt and close it. Take a mallet and bonk the bolt handle a couple times......that's it.
I don't pretend to know how much torque that equates to, but it is enough. I have built several rifles since I was told about this method, and so far, it takes quite a bit more to get them loose than it did to seat them in the first place.
I think the reason for this, is that a RH twist barrel will be constantly tightening the barrel to the action. If I ever have call to install a LH twist barrel (like is found on the British Enfield) I will be putting the barrel on the same way I took it off.....with an action wrench, but other than that one instance, they will be installed with much less vigor and gusto.

[nekshot]

Thanks, I feel better already. As you approach passing things on to next generation I simply move with a little more caution than before.

[leftiye]

This horse has been beaten pretty hard already. I think you need to ask some of the top BR smiths in the Country if 35 pounds is enough.

He already has.

[B R Shooter]

He already has.

Really? Who?

Perhaps maybe read the book "Rifle Accuracy Facts" by Harald Vaughn as well.

[Willbird]

Really? Who?

Perhaps maybe read the book "Rifle Accuracy Facts" by Harald Vaughn as well.

I read the book but loaned out my copy a few years back and never got it back . I do not recall what he said about tightening barrels, tons of other good stuff in there. It seems like you and I were the only people to read it so far .

Bill

[HollowPoint]

It this point I think we're just beating the maggots feasting on the carcass of this
dead horse.

I'm pretty sure I asked this very same question once before; just before undertaking
an Enfield re-barreling project.

It never hurts to ask; it's when you dive into your projects without having asked that
it may hurt you.

HollowPoint

[leftiye]

Felix was a benchrest shooter for a lot of years, and has been all through this for years and years. Y'all need to re-read Goodsteel's post (another who knows whereof they speak). As long as it doesn't come loose ( and I'd torque it well, but not excessively), nor move in the threads (I've heard of that happening - no problem, just re-tighten the barrel) it don't matter. What does matter is the fit together of the threads, and you can lap them.

[felix]

Actually, some smithies believe larger truncated cone threads are better made uniform than those smaller and sharper triangular shaped. As long as the vibes are consistent it makes no difference engineering wise. ... felix

[Willbird]

Actually, some smithies believe larger truncated cone threads are better made uniform than those smaller and sharper triangular shaped. As long as the vibes are consistent it makes no difference engineering wise. ... felix

Those would be maybe ACME threads ?? Or even Buttress ??

[B R Shooter]

Vaughn talked about a different thread type, but I don't recall the name. What I do recall however, when Jerry Stiller started making his actions, he researched many things, including thread type. Stiller is an engineer that works for Raytheon, and makes stuff our Govt won't talk about. He couldn't find a good reason to get away from the standard vee thread. He did however cut the threads in his actions with an .0007" taper, tighter to the rear. He has since stopped doing that because of the reason stated above, where someone wants to make the thread fit too tight. You don't screw around (no pun) with stainless steel and tight threads.

As an aside, Stiller is the one who designed the .062" firing pin, and may have patented it, not sure. But his research proved a large firing pin was a big contributor in blanking primers. You gotta try real hard to blow a primer with an .062" pin.

Anyway, Vaughn was big on torquing barrels, with his instruments he could see the vibrations with not-so-tight barrels. He tried many types of thread lube trying to find the best that would allow more torque. While I admit I have shot barrels that were not particularly torqued tight on my BR guns, but it's not the right thing to do. 90 pounds is not a lot of torque on a 1" or 1-1/16" thread. Some do more, some less. But in the BR game, anything you can do to limit vibrations, or control vibrations, is best. On a hunting gun, you'll never know it. But why chance it? Crank it up and forget about it.

[felix]

I had a tough time in 1972 deciding which job to take with Raytheon or Pratt&Whitney. Rockets or jets. Route 128 or I91. Tough decision. Looking back, the rocket job would have been more fun because the job emphasized real-time hardware versus massive data manipulation at Pratt. The latter was more lucrative to me then as was during any time after. ... felix

[Willbird]

Boy that really irks me about that book, I loaned it to a friend and never got it back, now it is out of print.