Action wrench: torque or no torque

C

chino69

Guest
I just had several barrels chambered and set up by a well respected gunsmith to be used in two switch barrel rigs. They are both trued Remington actions, with oversize ground recoil lugs. I bought a T-handled rear action wrench for removing and installing the barrels from Kelbly's; a very well made piece of equip't. The overboard side of me wants to weld a 1/2" drive socket on the end of the wrench so I can use a torque wrench to install the barrels to the same torque every time. The common sense side of me says the T-handle is good enough. What say you gents who have more experience in this?
Thanx in advance,
Chino69
 
George Kelbly will tell you that a full grunt on the handles is enough. For sure, just snapping them in place, as many do, is not enough.

If you are going to torque them, how much?? Vaughn says something like 250 ft/lb. Several years of changing barrels has told me that about 125-150 ft/lb is about right for benchrest actions.

Is torquing to the same each time the best....can't hurt. Is it necessary....who knows....as long as you put the same amount of grunt into each change.
 
Grunt vs. torque

JerrySharrett said:
George Kelbly will tell you that a full grunt on the handles is enough. For sure, just snapping them in place, as many do, is not enough.

If you are going to torque them, how much?? Vaughn says something like 250 ft/lb. Several years of changing barrels has told me that about 125-150 ft/lb is about right for benchrest actions.

Is torquing to the same each time the best....can't hurt. Is it necessary....who knows....as long as you put the same amount of grunt into each change.
Click to expand...

Jerry,
I'm leaning toward the grunt factor. How much force would be required to dimensionally change headspace or any other critical factor? I don't know but can guarantee it's more than I can personally deliver to the wrench. For all practical purposes, I think a good grunt should suffice. Forty ft/lbs. is about equal to a good grunt and a random sampling of 'calibrated grunters' seem to agree that any more than 40 ft/lbs. is not necessary.
Thanx,
Chino69
 
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chino69 said:
Jerry,
I'm leaning toward the grunt factor. How much force would be required to dimensionally change headspace or any other critical factor? I don't know but can guarantee it's more than I can personally deliver to the wrench. For all practical purposes, I think a good grunt should suffice. Forty ft/lbs. is about equal to a good grunt and a random sampling of 'calibrated grunters' seem to agree that any more than 40 ft/lbs. is not necessary.
Thanx,
Chino69
Click to expand...

Has anyone ever seen them loosen up after shooting a few rounds?
 
I did a search for posts by Jackie about tightening a barrel, he has made some excellent explanations how and why... here is what he posted... He also made some comments about not shooting as well if it is not sufficiently tight... but I haven't found that reference yet...

One method by Jackie Schmidt:

This is really a subjective figure. And in reality, has little to do with what you are trying to accomplish. That being, establishing the correct load, (stretch, tension), between the barrel and the action. There are quite a few variables that can cause a torque figure to fail to accomplish this.
Here is how I do it. I install the new barrel, and pull it reasonably tight. I then loosen it, and then lightly bump it against the shoulder, making sure that it is firmly seated and all slack is out. I then take a pencil and draw a mark from the action to the barrel. I then tighten the barrel to where these two marks have about 3/32 apart. This way, I can see that the barrel did indeed advance on the thread, and is under what I consider good tension.
I did take the time to modify my home made action wrench to use a socket, so I could use a torque wrench and see exactly what I was exerting. The figure came out to about 125 ft lbs. That is using a standard anti-seize compound on the face and the threads.

Maybe I should add: I don't think you can go wrong with any method Jackie adopts. He is a highly qualified precision machinist, does his own gun work, and is a highly successful Benchrest competitor.
 
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torque

If you want a threaded joint to be properly torqued it is related to the yield strength of the material. The good data related to this has been proven with cyclical loads as in connecting rod bolts. In applications where you have access to both ends of the bolt, you measure how much the bolt stretches as you tighten it. In a barrel application it probably doesn't matter.
 
Torque

robdaniel said:
If you want a threaded joint to be properly torqued it is related to the yield strength of the material. The good data related to this has been proven with cyclical loads as in connecting rod bolts. In applications where you have access to both ends of the bolt, you measure how much the bolt stretches as you tighten it. In a barrel application it probably doesn't matter.
Click to expand...

We torque huge nuts on high pressure turbine shells by measuring the amount of stud elongation. A heater rod is inserted into the body of the stud, the stud grows, and the nut is torqued with a Hy-Torq hydraulic tool. The amount of elongation is equivalent to a calculated torque. This is required for the electric utility industry. For my purposes, a couple of good grunt turns on the wrench should be good enough.
Chino69
 
40 ft. lbs. with a grunt. Come on. You can do better than that. :) I once had a friend that wrung all the studs off his friends Chrysler wheel to get it changed before bringing it in and discovering that the L on the stud meant left hand thread. I guess he had a high torque grunt. I like the torque wrench idea.
 
chino69 said:
Jerry,
I'm leaning toward the grunt factor. How much force would be required to dimensionally change headspace or any other critical factor? Thanx,
Chino69
Click to expand...

Considerably more than a George Kelbly grunt and a half, and much more than 200 ft/lb would be required to distort the barrel/action joint..

Just as a rough idea, a 1-8tpi bolt at 125 ft/lb will give a clamp load of 15,000 pounds, way below the yield strength of 416 SS. A 1-16 tpi would be about twice the clamp load, just as a jug-handle estimate.
 
Torque

WhelenMan said:
40 ft. lbs. with a grunt. Come on. You can do better than that. :) I once had a friend that wrung all the studs off his friends Chrysler wheel to get it changed before bringing it in and discovering that the L on the stud meant left hand thread. I guess he had a high torque grunt. I like the torque wrench idea.
Click to expand...

Well I came up with the 40 ft./lbs. from a previous post talking about the torque on the Savage barrel nut. The factory torques the barrel nut to
70 ft/lbs; ref. Machine Design article published 8/24/2006 "Keeping Firearms on Target". During discussion around this subject, other Savage owners revealed they torque their barrel nuts to approx. 40 ft./lbs.. I borrowed a calibrated torque wrench from work and torqued the nut to 40 ft/lbs. on my Savage switch barrel rig and it was plenty. The next time I changed a barrel I torqued the barrel nut by feel and it was plenty. It was probably pretty close to 40 ft/lbs. +/- 5 ft/lbs. I'm just trying to establish a real world practical solution without going overboard. It's also interesting to see how other people do it so that everyone can learn something in the process.
Chino69
 
Torque

JerrySharrett said:
Considerably more than a George Kelbly grunt and a half, and much more than 200 ft/lb would be required to distort the barrel/action joint..

Just as a rough idea, a 1-8tpi bolt at 125 ft/lb will give a clamp load of 15,000 pounds, way below the yield strength of 416 SS. A 1-16 tpi would be about twice the clamp load, just as a jug-handle estimate.
Click to expand...

Jerry,
That's the answer I was looking for and for my purposes, a grunt and a half will probably suffice without going overboard. Just for comparison and to make this interesting, the following question comes to mind. Would you think there would be any difference in accuracy/performance if the torques were varied and the resultant groups compared? For example, torque the barrel to 50 ft/lbs. and fire a group. Torque it next to 75, 100, & 125 ft/lbs. and compare the results. There may or may not be any difference but at least there would be quantitative and qualitative data to back up a given torque. Just a thought to throw out there. Maybe people have done this and can report back. If not, it may warrant me trying this at a later date.
Chino69
 
chino69 said:
Jerry,
That's the answer I was looking for and for my purposes, a grunt and a half will probably suffice without going overboard. Just for comparison and to make this interesting, the following question comes to mind. Would you think there would be any difference in accuracy/performance if the torques were varied and the resultant groups compared? For example, torque the barrel to 50 ft/lbs. and fire a group. Torque it next to 75, 100, & 125 ft/lbs. and compare the results. There may or may not be any difference but at least there would be quantitative and qualitative data to back up a given torque. Just a thought to throw out there. Maybe people have done this and can report back. If not, it may warrant me trying this at a later date.
Chino69
Click to expand...
As to qualitative data of whether 50 ft/lb or 150 ft/lb would have accuracy differences, the only way I could think of proof would be to conduct an extensive test in a controlled atmosphere like a tunnel. Then within that test, a centerfire barrel basically starts deteriorating in accuracy soon after it is broken in, I really see no way to get indisputable proof.

We know that a loose barrel will preform noticeably worse than a tight barrel. I still say that the "snap barrel" tighteners are on risky territory. Until someone proves different I will continue to tighten my barrels to about a grunt and a half (125 ft/lb or there abouts).
 
Grunt factor

JerrySharrett said:
As to qualitative data of whether 50 ft/lb or 150 ft/lb would have accuracy differences, the only way I could think of proof would be to conduct an extensive test in a controlled atmosphere like a tunnel. Then within that test, a centerfire barrel basically starts deteriorating in accuracy soon after it is broken in, I really see no way to get indisputable proof.

We know that a loose barrel will preform noticeably worse than a tight barrel. I still say that the "snap barrel" tighteners are on risky territory. Until someone proves different I will continue to tighten my barrels to about a grunt and a half (125 ft/lb or there abouts).
Click to expand...

Thanks Jerry,
A grunt and a half works for me. If I ever conduct a test, I'll post the results but I may resort to strong drink and women of ill repute before that time comes.
Chino69
 
chino69 said:
Thanks Jerry,
A grunt and a half works for me. If I ever conduct a test, I'll post the results but I may resort to strong drink and women of ill repute before that time comes.
Chino69
Click to expand...
Lets go with the strong drink and women of ill repute. I didn't realize we had a choice!!
 
Barrel Torque

I installed my new Kreiger on a 40X action last night with a grunt and a half of torque. I can guarantee this barrel will not loosen without the aid of a barrel vise and action wrench. I really don't think there will be any measurable difference between 1 1/2 grunts and 125 ft/lbs. of calibrated torque.
Chino69
 
Barrel Torque?

I came at it with a simple minded approach that has worked out fine for me. The lug nuts on my car call for 100 ft-lbs and that's what I use on my barrels. Its worked fine, so I'll stick with it.
 
how tight is the nut

75# to 90# don't use a raceway wrench, could twist action.
 
Is there a reason why 40lb torque on a Savage barrel nut might be OK but a barrel screwed directly into the action should be more? I have a half dozen rifles that the barrels have been "snapped tight". What is the risky part? I hate to take them all apart if it is not necessary. Kenny
 
Savage barrel nut torque

sicero said:
Is there a reason why 40lb torque on a Savage barrel nut might be OK but a barrel screwed directly into the action should be more? I have a half dozen rifles that the barrels have been "snapped tight". What is the risky part? I hate to take them all apart if it is not necessary. Kenny
Click to expand...

That's a good question; I was thinking along the same lines. Bear in mind the Savage barrel screws into the action until the headspace is correct and then the barrel nut is torqued. This puts the threaded portion in tension as opposed to compression as in the standard Remington design. What is the difference in regards to harmonics and accuracy? Vaughn discusses this in his book 'Rifle Accuracy Facts' and when I asked Savage why they torque to 70 ft/lbs. the phrase 'impulse moment' came up. Please note that the Savage rep. did not specify or mention a torque due to obvious legal implications. I'm curious as to whether any out there have an explanation for this.

My guess would be that with the threaded portion of the barrel being in tension, there is a specific harmonic node generated at the time of firing. Anyone familiar with standing waves and sinusoidal waveforms will understand what I'm getting at. Anyone out there that can add?
Chino69
 
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