J
JEC
Guest
Getting set up to switch barrel on a Rem 700 action....what is the approximate torque when using a rear port wrench? Any "tricks" that will make the job easier? What do you use as an anti-galling compound? Thanks
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f d shuster
Guest
torque
jec: On the advice of my gunsmith who set-up all 4 of my switch-barrel rifles, I've been using 65 ft. lbs., measured with Snap-on auto mechanics 200 ft. lb. capacity torque wrench. Also using the Davidson barrel vice and rear port entry wrench, both purchased from Sinclair. "Permatex" anti-sieze (just a minmal amount), applied with each barrel change. Wrapping my barrels, blued chrome moly and stainless glass beaded & polished, with several layers of heavy brown shopping bag paper and have never marked a barrel yet. Am using the Kleindorst recoil lug tool (purchased from Brownell) to keep the recoil lug in position when torqueing down the barrel. All 4 rifles are Rem 700's. Have go-gages for each ctg to verify headspace. Have verified fired case headspace o.a.l.'s and they remain identical before and after barrel changes.
jec: On the advice of my gunsmith who set-up all 4 of my switch-barrel rifles, I've been using 65 ft. lbs., measured with Snap-on auto mechanics 200 ft. lb. capacity torque wrench. Also using the Davidson barrel vice and rear port entry wrench, both purchased from Sinclair. "Permatex" anti-sieze (just a minmal amount), applied with each barrel change. Wrapping my barrels, blued chrome moly and stainless glass beaded & polished, with several layers of heavy brown shopping bag paper and have never marked a barrel yet. Am using the Kleindorst recoil lug tool (purchased from Brownell) to keep the recoil lug in position when torqueing down the barrel. All 4 rifles are Rem 700's. Have go-gages for each ctg to verify headspace. Have verified fired case headspace o.a.l.'s and they remain identical before and after barrel changes.
jackie schmidt
New member
A Little Light
Just my opinion, but 65 ft pounds seems a tad light for a Remington. I think no less than 100 would be more like it. On my Farley Actions, which have the same tenon thread, I use 120.
As for the rear port wrench, just be sure you get one that places all of the torque at the front, reducing the possibility of twisting the action in way of the magazine cut-away. Sinclair and Kelbys have about the best I have seen. The Kelbly will also work on a Panda and a Viper.........jackie
Just my opinion, but 65 ft pounds seems a tad light for a Remington. I think no less than 100 would be more like it. On my Farley Actions, which have the same tenon thread, I use 120.
As for the rear port wrench, just be sure you get one that places all of the torque at the front, reducing the possibility of twisting the action in way of the magazine cut-away. Sinclair and Kelbys have about the best I have seen. The Kelbly will also work on a Panda and a Viper.........jackie
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nhkuehl
Guest
Barrel torque
For some reason 50-80 ft. lbs. sticks in my mind, but I did an online search and found anywheres from 25-150 ft. lbs.
I watched a benchrest shooter switch barrels on a BAT action and he ran it to the shoulder by hand and then marked the barrel and action and then rotated the barrel about 1/4" past that mark with an action wrench; no torque reading. I don't have any idea what kind of torque that would give.
For what it's worth: The Complete Illustrated Guide to Precision Rifle Barrel Fitting - John L. Hinnant, 3rd Edition Revised August 2003 states 1/8" - 3/16" past hand tight and cautions about over tightening. I couldn't find my notes from Trinidad
nhk
For some reason 50-80 ft. lbs. sticks in my mind, but I did an online search and found anywheres from 25-150 ft. lbs.
I watched a benchrest shooter switch barrels on a BAT action and he ran it to the shoulder by hand and then marked the barrel and action and then rotated the barrel about 1/4" past that mark with an action wrench; no torque reading. I don't have any idea what kind of torque that would give.
For what it's worth: The Complete Illustrated Guide to Precision Rifle Barrel Fitting - John L. Hinnant, 3rd Edition Revised August 2003 states 1/8" - 3/16" past hand tight and cautions about over tightening. I couldn't find my notes from Trinidad
nhk
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NesikaChad
Guest
Get yer whips, I'm sure I'll take a lickin.
First decide if you are concerned about group size or group center, or both.
If all you care about is group size then torque the thing to whatever you want. I've seen well fitted tennons screwed on hand tight that shoot some very nice groups at closer distances.
Then it shoots another nice group someplace else.
If having a repeatable zero is important to you then I encourage you to consider snugging up the barrel. Exactly how much is highly debated and pondered over. I have my magic number just like other folks do.
I'll use a Palma rifle as an example regarding group center. I've never done this but I feel pretty good stating that if I hand snugged a barrel on one of these rifles the shooter would probably unscrew it and beat me with it because he/she would be chasing zeros all over the creation. Never mind the other weird stuff it'd be doing to groups at 1K yards.
Hope this helped.
Chad
First decide if you are concerned about group size or group center, or both.
If all you care about is group size then torque the thing to whatever you want. I've seen well fitted tennons screwed on hand tight that shoot some very nice groups at closer distances.
Then it shoots another nice group someplace else.
If having a repeatable zero is important to you then I encourage you to consider snugging up the barrel. Exactly how much is highly debated and pondered over. I have my magic number just like other folks do.
I'll use a Palma rifle as an example regarding group center. I've never done this but I feel pretty good stating that if I hand snugged a barrel on one of these rifles the shooter would probably unscrew it and beat me with it because he/she would be chasing zeros all over the creation. Never mind the other weird stuff it'd be doing to groups at 1K yards.
Hope this helped.
Chad
F
f d shuster
Guest
torque
jackie: I've been using 65 ft. lbs. since the "beginning", ( hundreds of rounds fired with each of the 4 rifles), and no problems what-so-ever. With his more than 40 yrs. experience, my 'smith has never failed to provide me with excellent advice, yet another example of: "it works for me".
jackie: I've been using 65 ft. lbs. since the "beginning", ( hundreds of rounds fired with each of the 4 rifles), and no problems what-so-ever. With his more than 40 yrs. experience, my 'smith has never failed to provide me with excellent advice, yet another example of: "it works for me".
JerrySharrett
Senile Member
I'm with Jackie, 65 ft/lb is no where near enough. Even with perfectly matched thread profles on the action and tenon, 65 ft/lb just will not properly load the joint.
That diameter threaded joint, to make a solid mechanical joint could go to 750 ft/lb or so. Properly machined barrels do not need that much though.
I can't find my usual reference but this will give you the idea;
http://www.zerofast.com/torque.htm
Keep in mind this chart is for maximum loading based on yield. Rifle barrels are not primarily load bearing though.I know of an old benchrest gunsmith who made enough to buy a small farm and 200 head of cattle charging $20 to "fix" benchrest rifles that would not tune properly.
Scope fixers love loose barrels too!!
JerrySharrett
Senile Member
Here is a better example to give you an idea of threaded joint strength.
http://raskcycle.com/techtip/webdoc14.html
Notice that even down to an SAE Grade 2 (stove bolts, etc) the suggested torque for a 1" bolt, wet, is 265 ft/lb.
Tensile strength for 416 SS, at about 350Bn is in excess of 120,000#.
http://raskcycle.com/techtip/webdoc14.html
Notice that even down to an SAE Grade 2 (stove bolts, etc) the suggested torque for a 1" bolt, wet, is 265 ft/lb.
Tensile strength for 416 SS, at about 350Bn is in excess of 120,000#.
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spencer313
Guest
Torque is an indicator of "stretch" or strain. But, as all the tables (and formulae) indicate, it depends upon friction, which is an unknown. If you tighten to a chosen rotation after shoulder contact ("1/8-in. on the circumference"), aren't you setting the "stretch" directly, regardless of torque?
Torque is a second-order effect, is it not?
Torque is a second-order effect, is it not?
C
captbill
Guest
barrel torque
I am by no means an expert but I was told by the smith that built my rifle (panda action) that the torque was not realy that important.
I am by no means an expert but I was told by the smith that built my rifle (panda action) that the torque was not realy that important.
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nhkuehl
Guest
Torque or stretch
I guess either one refers to compression in this case, and as compression increases so does friction. I'm sure there is a point of diminishing return, where you are no longer gaining anything by increased torque. It would be interesting to make a mock up and measure the torque required to 'stretch' by rotating 1/8", 3/16" and 1/4".
I haven't got any heat in my shop and won't attempt that now, but with a little warm weather and a few beers I make be inclined to experiment with that one But I'd probably just be re-inventing the wheel, because I'm sure someone has formulas for that out there.
I use a torque wrench as an upper limit because I've twisted off or stripped enough bolts in my life.
nhk
I guess either one refers to compression in this case, and as compression increases so does friction. I'm sure there is a point of diminishing return, where you are no longer gaining anything by increased torque. It would be interesting to make a mock up and measure the torque required to 'stretch' by rotating 1/8", 3/16" and 1/4".
I haven't got any heat in my shop and won't attempt that now, but with a little warm weather and a few beers I make be inclined to experiment with that one
But I'd probably just be re-inventing the wheel, because I'm sure someone has formulas for that out there.I use a torque wrench as an upper limit because I've twisted off or stripped enough bolts in my life.
nhk
jackie schmidt
New member
Torque
Torque is indeed an abiguous term. Many things can affect how "torque" is being applied as it relates to the actual holding capability of the threaded joint.
Any body who is involved in Racing Engines, or the assembling of large Diesel Engines, knows that most criticle securing bolts are installed to apre-determined stretch. For instance, the proper stretch for a 7/16 big block Chevy boron rod bolt was .009 inch. Now, the proper torque spec in the manual was 68 ft lbs. But it sometimes took as much as 85 ft lbs toachieve the proper stretch.
Which brings me to a point. In order for a threaded joint that is designed to secure two pieces together with absolutly no fear of movement, to do it's job, you MUST place the joint in tension. That means you are either stretching metal, or placing it in compression.
What I do on a 16 tpi is I snug the barrel, then I place a pencil mark between the reciever and the barrel.I then tighten untill there is 3/32 inch between the marks. That usually takes about 120 ft lbs. But, by using the witness marks, I know that the barrel actually advanced on the threaded joint.
For what it is worth, Kelbly recommends about 120 ft lbs as well. They will also tell you that they have cured a lot of ills in a customers bad shooting rifle by simply tightenning the barrel to a proper tension........jackie
Torque is indeed an abiguous term. Many things can affect how "torque" is being applied as it relates to the actual holding capability of the threaded joint.
Any body who is involved in Racing Engines, or the assembling of large Diesel Engines, knows that most criticle securing bolts are installed to apre-determined stretch. For instance, the proper stretch for a 7/16 big block Chevy boron rod bolt was .009 inch. Now, the proper torque spec in the manual was 68 ft lbs. But it sometimes took as much as 85 ft lbs toachieve the proper stretch.
Which brings me to a point. In order for a threaded joint that is designed to secure two pieces together with absolutly no fear of movement, to do it's job, you MUST place the joint in tension. That means you are either stretching metal, or placing it in compression.
What I do on a 16 tpi is I snug the barrel, then I place a pencil mark between the reciever and the barrel.I then tighten untill there is 3/32 inch between the marks. That usually takes about 120 ft lbs. But, by using the witness marks, I know that the barrel actually advanced on the threaded joint.
For what it is worth, Kelbly recommends about 120 ft lbs as well. They will also tell you that they have cured a lot of ills in a customers bad shooting rifle by simply tightenning the barrel to a proper tension........jackie
Joe Ponto
New member
One point not mentioned is lubrication. This obviously lowers the torque necessary to load the threads. Just keep the type of lub in mind when looking at torque values - often expressed in dry, oil film etc.
Oh and don't forget the wonderful calibration requirements for those precise instruments.
Oh and don't forget the wonderful calibration requirements for those precise instruments.
JerrySharrett
Senile Member
Calibrate? Why calibrate when we don't have a firm knowledge of what the torque should be.
I do wonder about some of these 40 year gunsmiths that suggest just snapping a barrel in place though.
For sure mine will be 100 ft/lb or greater, always.
Joe Ponto
New member
Simple. Repeatability...which is one point we strive for. If your torque wrench can't hold accurate torques over time...you have inconsistency. The inconsistency may or may not translate to issues down range.
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NesikaChad
Guest
Thoughts that someone might find useful:
I have learned it's wise to pull a receiver up to the shoulder several times before final assembling. The reason is no matter how good the lathe threads are they are going to have little boogers that peen over, wear off, and conform to the opposite thread being squished into them. This affects the surface contact and the clock positioning.
-It's been known to generate an occasional outburst of expletives when clocking a fluted barrel. . .
Torque. 5 years with an NHRA Competition Eliminator engine builder and race team schooled me on fastener tensile loading. As stated, the elongation of a fastener is a far more accurate means of determining this over a torque wrench. Friction coefficients are all over the place depending on the type of lubricant used during assembly, the surface hardness, finish, and coating of the thread, as well as, the thread's pitch. Lots of variables there. Temperature messes with it too to some degree.
All this is great and high minded, but trying to measure it on a rifle barrel tennon would be a bit of a challenge I think. I don't think it's really needed either. All we are trying to do is hold the dern thing still where's a connecting rod is accelerating at 5500 feet per second to a dead stop and back to 5500 feet per second 13,000 (actually 26,000) times a minute. (talking SB Comp E motors here) I don't mean to down play it as this is a subject I really try to pay close attention to when doing barrel work. It's one of the reasons why I tout about threading at the higher rpm ranges where carbide inserts reign king. It has to do with surface finish and that directly plays into how well a tennon snugs up. I like having a barrel "clam shut" when it contacts the shoulder. If it feels "squishy" I don't like it.
(how's that for high minded and scientific? Clam and squishy)
Bright shiny threads free of surface inclusions and a high shear strength grease will get you a long way. Make sure your shoulders are as square as you can make them and then pull the sucker up tight.
Then get out there and get to cooking the throat.
I have learned it's wise to pull a receiver up to the shoulder several times before final assembling. The reason is no matter how good the lathe threads are they are going to have little boogers that peen over, wear off, and conform to the opposite thread being squished into them. This affects the surface contact and the clock positioning.
-It's been known to generate an occasional outburst of expletives when clocking a fluted barrel. . .
Torque. 5 years with an NHRA Competition Eliminator engine builder and race team schooled me on fastener tensile loading. As stated, the elongation of a fastener is a far more accurate means of determining this over a torque wrench. Friction coefficients are all over the place depending on the type of lubricant used during assembly, the surface hardness, finish, and coating of the thread, as well as, the thread's pitch. Lots of variables there. Temperature messes with it too to some degree.
All this is great and high minded, but trying to measure it on a rifle barrel tennon would be a bit of a challenge I think. I don't think it's really needed either. All we are trying to do is hold the dern thing still where's a connecting rod is accelerating at 5500 feet per second to a dead stop and back to 5500 feet per second 13,000 (actually 26,000) times a minute. (talking SB Comp E motors here) I don't mean to down play it as this is a subject I really try to pay close attention to when doing barrel work. It's one of the reasons why I tout about threading at the higher rpm ranges where carbide inserts reign king. It has to do with surface finish and that directly plays into how well a tennon snugs up. I like having a barrel "clam shut" when it contacts the shoulder. If it feels "squishy" I don't like it.
(how's that for high minded and scientific? Clam and squishy
)Bright shiny threads free of surface inclusions and a high shear strength grease will get you a long way. Make sure your shoulders are as square as you can make them and then pull the sucker up tight.
Then get out there and get to cooking the throat.
Last edited by a moderator:
JerrySharrett
Senile Member
I understand where you are coming from Joe but do we not need to have a better understanding of a reasonable range of torque for a benchrest rifle barrel?
First thing, there should be an understanding that tenon shoulders must be square and well finished.
Second, threads must be of the proper profile with the action thread profile.
Third, application of a good thread lubricant before applying tightening torque. We sure don't want to torque a dry thread joint when many actions are of stainless steel and the barrel is stainless steel.
I have tried 10 foot pounds and 1000 foot pounds on a Mauser, and for one session, makes no difference in accuracy.
The Rem700 design has some problems compared to the Mauser design:
a) Round receiver not as easy to get apply torque
b) Receiver is thin, and may collapse.
c) No inner C ring means the only contact is on the barrel shoulder to the recoil lug. This stretches the threads of the barrel. If shooting stretches the threads further, there is the concern that the recoil lug compression may be lost for an instant, and the barrel could eventually unscrew from shooting.
Here is a derivation of the Rem700 needing 200 foot pounds if the threads are greased:
http://www.snipershide.com/forum/ub...1137812&Searchpage=1&Main=103627&#Post1137812
I am suspicions that is why the Remington factory is putting that glue goop on the Rem700 threads.
The Rem700 design has some problems compared to the Mauser design:
a) Round receiver not as easy to get apply torque
b) Receiver is thin, and may collapse.
c) No inner C ring means the only contact is on the barrel shoulder to the recoil lug. This stretches the threads of the barrel. If shooting stretches the threads further, there is the concern that the recoil lug compression may be lost for an instant, and the barrel could eventually unscrew from shooting.
Here is a derivation of the Rem700 needing 200 foot pounds if the threads are greased:
http://www.snipershide.com/forum/ub...1137812&Searchpage=1&Main=103627&#Post1137812
I am suspicions that is why the Remington factory is putting that glue goop on the Rem700 threads.
Joe Ponto
New member
That is absolutely true but given the current action designs, I am not sure why we are talking about it...unless we have a different system in mind.
PR2Shooter
New member
60,00 PSI and the twist of the barrel will tighten it nicely with each shot. Until it ist finished "moving" ........ever notice those suckers are tight as heck after 500 rds!