How many degrees of rotation do you get when torquing a barrel?

[tonyben]

In the M14 world, I have my method down to a science. I can trim the shoulder for the barrel to hand time at 15˚ before center and cut my chamber headspace before I torque the barrel on. With a nice 2 foot lever, I know what 80 foot pounds feels like and I know what my headspace will be. However, this is with 10 TPI ACME threads on the barrel. After torquing those barrels, I can count on headspace closing 0.003"

How many degrees do you typically get from hand tight to 80 foot pounds with a 16 TPI standard thread? How much does your headspace close from hand tight to final torque?

I recently screwed on a Remington CSR barrel extension on to a Proof barrel and I only got about 5 or 7˚ of rotation before hitting the torque. I got my headspace set to 1.631" (308 Win), but I underestimated the amount of rotation I thought I'd get. I was also thinking the setup I have to clamp around the barrel extension might give me a false torque setting by applying clamping pressure around the barrel extension. I clamped on the end, not crushing the threads, but I wonder if even that was enough to put stress on the thread area.

There is no tool for installing barrel extensions on the CSR barrel extensions, so I had to make one. I'll have to see about making a different tool that mimics bolt lugs.

Tony.

 

[jackieschmidt]

I cannot give it in degrees.
When I tighten a barrel on my Benchrest Rifles, I snug the barrel, then with a Sharpie Pen, I put a line between the action ring and barrel.

At 80 fl pounds, there will be about 3/32 space between the marks.

I am not concerning myself with having to clock the barrel in any particular position.

 

[Rat Rifle]

I cannot give it in degrees.
When I tighten a barrel on my Benchrest Rifles, I snug the barrel, then with a Sharpie Pen, I put a line between the action ring and barrel.

At 80 fl pounds, there will be about 3/32 space between the marks.

I am not concerning myself with having to clock the barrel in any particular position.

Not trying to derail the thread, but how important is clocking the barrel on a bench rest rifle ?

 

[SKWERLZ]

I get about 1/8 of movement at 100 ft lbs.
Approximately 11.459 degrees.
My tenon is 1.0625 x 20tpi

 

[BuffaloBill]

I cannot give it in degrees.
When I tighten a barrel on my Benchrest Rifles, I snug the barrel, then with a Sharpie Pen, I put a line between the action ring and barrel.

At 80 fl pounds, there will be about 3/32 space between the marks.

I am not concerning myself with having to clock the barrel in any particular position.

Assuming a 1.25” shank diameter, 3/32” between the marks would be about 8.6 degrees. I guess if the sharpie mark was 1/16” wide, then add another 5.7 degrees, or 14.3 degrees rotation. Please double check my math.

 

[AlNyhus]

I do mine Jackie-style. At 100 lbs/ft., it's like this:

 

[DaveTooley]

In the M14 world, I have my method down to a science. I can trim the shoulder for the barrel to hand time at 15˚ before center and cut my chamber headspace before I torque the barrel on. With a nice 2 foot lever, I know what 80 foot pounds feels like and I know what my headspace will be. However, this is with 10 TPI ACME threads on the barrel. After torquing those barrels, I can count on headspace closing 0.003"

How many degrees do you typically get from hand tight to 80 foot pounds with a 18 TPI standard thread? How much does your headspace close from hand tight to final torque?

I recently screwed on a Remington CSR barrel extension on to a Proof barrel and I only got about 5 or 7˚ of rotation before hitting the torque. I got my headspace set to 1.631" (308 Win), but I underestimated the amount of rotation I thought I'd get. I was also thinking the setup I have to clamp around the barrel extension might give me a false torque setting by applying clamping pressure around the barrel extension. I clamped on the end, not crushing the threads, but I wonder if even that was enough to put stress on the thread area.

There is no tool for installing barrel extensions on the CSR barrel extensions, so I had to make one. I'll have to see about making a different tool that mimics bolt lugs.

Tony.

I use a rear entry tool. Mine came from Remington but I've made them for other oddball things.

 

[tobnpr]

There's some apples to oranges here.
Barrel rotation beyond contact is affected by the perpendicularity of the shoulder to the threads, and the surface finish of the both the barrel shoulder and receiver ring.
Rough machining artifacts on either or both of the mating surfaces will "crush" out under torque allowing for more rotation and closure of headspace. Ditto with imprecise perpendicularity- it will allow for rotation beyond contact.

Perfectly faced and threaded parts will have very little rotation beyond contact. As others have said, typically less than 10 degrees- but that's a pretty useless metric IMO. What matters is the additional travel under torque, which is typically one to two thousandths when correctly machined. With production factory parts, it's a crapshoot.

JMOYMMV

 

[DaveTooley]

The amount of rotation is dependent on more than torque. 70-80 ft lbs is not much for say 1 1/16'-16 thread. Perpendicularity of the treads and shoulder. Fit of the treads has a lot to do with it also. Loose threads will square up the shoulders easier and allow the treads to find their resting place.
My first job where timing an extension was called for worked out well. I did 150 gas gun barrels where the gas port had to be timed to fall in the groove. Good extensions and good machine work and I got all 150 to time up. I planned for about 1/8" of rotation when torqued to 80 ft lbs
Oh your question about HS crush. I have never seen more than maybe a few tenths. It something I have never seen or had to deal with.

 

[WayneShaw]

With both surfaces right, you can snap a barrel on with your hand. But you won't get it back off by hand.

 

[jackieschmidt]

I do mine Jackie-style. At 100 lbs/ft., it's like this:

^^^^^^^^^^^
This.
I mainly do it to insure the barrel did actually tighten.

 

[AlNyhus]

^^^^^^^^^^^
This.
I mainly do it to insure the barrel did actually tighten.

You bet!

 

[Judd]

The things that keep me up at nite…

Timing straight flutes and muzzle breaks I will say, early on it seemed pure luck with good intentions and plans…now it feels intentional…but it took a while to get a feel for it. I mark what I’m trying to hit and stop just 1/16-1/8 shy of my mark…once torqued it’s good.

 

[SKWERLZ]

^^^^^^^^^^^
This.
I mainly do it to insure the barrel did actually tighten.

Same
I have a mark that lines up with the key on the lug that indexes it to the action.

 

[DaveTooley]

Put a barrel on a Defiance Deviant action today. Just for giggles I kept track of things. About 1/16" rotation with 80 ft/lbs and ZERO change in HS. The bolt dragged on the go gage in the lathe and nothing changed after installation. YMMV

 

[RGRobinett]

Put a barrel on a Defiance Deviant action today. Just for giggles I kept track of things. About 1/16" rotation with 80 ft/lbs and ZERO change in HS. The bolt dragged on the go gage in the lathe and nothing changed after installation. YMMV
View attachment 1660071

^^^^^^^ RG

 

[Old Navy]

The amount of rotation is dependent on more than torque. 70-80 ft lbs is not much for say 1 1/16'-16 thread. Perpendicularity of the treads and shoulder. Fit of the treads has a lot to do with it also. Loose threads will square up the shoulders easier and allow the treads to find their resting place.

Right on!