butchlambert
Site $$ Sponsor
I have built a rifle or two. If you are referring to the basic design of a bolt action, yes the design goes back to the 1800s. My rifles do not have witness marks.
How much torque on barrels
- Thread starter Grimstod
- Start date
Jay Christopherson
Not An Admin
Tozguy said:
If everything is square (shoulder/threads/action, etc...), you shouldn't be able to turn a barrel 1/8 - 1/4 turn past stop (that is, registering to the shoulder). Stopping at the shoulder is just that - stopped. You might be able to tighten a bit past there, but with very little movement overall. Otherwise, what was the whole point of head-spacing your barrel? I certainly don't torque the action down while chambering and checking headspace...
If you *can* turn a barrel another 1/8 - 1/4 turn after it has stopped against the shoulder, there's a problem - things are not square.EDIT: I'll limit my comments to modern actions.
Keith Glasscock
Gold $$ Contributor
On my switch-barrel rig, the difference between hand tight and 60 ft-lbs is several thousandths of an inch in circumferential surface movement.
That said, I do not allow any anti-sieze to get between to shoulder (SS) and action face (CM) - only the threads. If there is anything between, I'm sure there would be a difference.
That said, I do not allow any anti-sieze to get between to shoulder (SS) and action face (CM) - only the threads. If there is anything between, I'm sure there would be a difference.
Erik Cortina
Team Lapua Brux Borden Captain
Busdriver, how much is "several thousands"?
NYM said:
Understand what?
On a custom barrel with 16tpi threads, 60 ft-lbs added after tightening by hand, only nets me 1/32nd of a turn or .002'' less headspace (by calculation). I factor in this amount when cutting the chamber. The barrel has been removed once and the same torque brought it back to the same position. I can understand that old military stuff might be a different game entirely if it takes 500 ftlbs to remove one.
X Ring Accuracy said:
What is your definition of 'self taught'?
I would be hard pressed to identify anybody participating in this thread whose hasn't taught themselves something. Isn't experience a good teacher? It seems to me its not about HOW you learned but WHAT you learned. Formal training and a diploma is no garantee that you will do good work.
Keith Glasscock
Gold $$ Contributor
Erik,
Let me first say, I have not, and will not scribe a line in the receiver to get a good measurement.
I ended up measuring out of curiosity when the action didn't seem to move during torquing. My best guess (using calipers) is .020"
Let me first say, I have not, and will not scribe a line in the receiver to get a good measurement.
I ended up measuring out of curiosity when the action didn't seem to move during torquing. My best guess (using calipers) is .020"
Erik Cortina
Team Lapua Brux Borden Captain
Busdriver said:
I don't scribe my actions either.
You mean .020" around the circumference?
Warren Dean
Team Savage F-TR
Just pull till you fart and call it good. 
Keith Glasscock
Gold $$ Contributor
Yes, around the circumference. Best guess, I'm moving it about 3 degrees.
Understand, that is from as tight as I can get it with my hand, and no, I'm not that strong.
The barrels I have right now literally slam into place. Some of my other rifles are a touch more mushy. Guess I'm using a good rifle smith (on the switch-barrel).
Understand, that is from as tight as I can get it with my hand, and no, I'm not that strong.
The barrels I have right now literally slam into place. Some of my other rifles are a touch more mushy. Guess I'm using a good rifle smith (on the switch-barrel).
Hi Donovan, Thank you for your welcome. In Answer to your questions Number 1 Yes I build weapons but only one kind. I use old Mosin Nagant receivers to build some pretty wild target rifles. I know nothing about Remington or Savage -- but Mosins I have researched extensively. I'm 60 years old and an IBM certified machinist and industrial mechanic 45 years worth - also a certified Harley Davidson schooled mechanic. Yes I use forged steel receivers in my builds cause there cheap [25-35 dollars] and they can be fixed up to do the job needed. I'm not in the same league as you gentlemen - I make junk work. I can not afford a thousand dollars for a Bat receiver.[my favorite] I did shoot a 1.5 MOA group at a 1000 yd my first try with my home made rifle. I'm sure there are many people here who can do better. As far as the 27 degrees past contact - it was arrived at by disassembling - cleaning and oiling - then tighten to the original witness marks. Till I get some reliable information on these antique receivers, thats how they go back together. 37 million Mosins made just in the Soviet Union - I think they knew what they were up to. I'm searching for information as to the original factory build specs.. I've written Sako and will try to get what I can from the Westinghouse and Remington archives. I have read a lot about switch barrel rifles. I can see with competition grade receivers were that would be an advantage, with the Mosin receivers selling for 25-35 dollars a switch barrel Mosin has no advantage. I hope this answers some questions about me.dmoran said:
carlsbad
Lions don't lose sleep over the opinions of sheep.
I'm a physicist/mechanical engineer with a lot of experience in threaded joints. I use a technique that I learned in the nuclear industry. Don't know if it helps but it can't hurt. It is called embeddment and goes like this (this gets a bit technical so if you want you can skip to the last two paragraphs):
If both sets of threads are perfect 60 degree V's like you draw them on paper with no dings, gouges of imperfections, when you snug them up they will make full contact and any further tightening will be straining the metal (stretching it). In this case, the threads are 16tpi (remington) which means .062" per revolution. so those turning it 1/4 turn are/would be stretching the tenon .015" which is way beyond the yield strength of the steel.
Of course that isn't what is really happening. First the threads aren't perfect and second there are some real world issues such as lube that gets squeezed out and joint alignment issues (probably small with a good gunsmith), etc. So what most of that 1/4 turn is doing is working through all of the imperfections before you start stretching the tenon. So depending on how much turn it takes to start stretching the tenon, 1/4 turn could be anywhere from moderately tight to breaking it. So i don't like using x/y turn past snug for this application. I'm sure some guys make it work but they probably modify it based on feel and are actually doing a torque by experience method and experience almost always works.
Now to calculate a torque isn't that hard. You want to usually torque to 50% of yeild which on a quality action is probably somewhere around 75ksi for carbon steel, not sure about what type of stainless is used. Austenitic stainless is usually much less than that. The force from torquing if T=.2F/D where D is thread diameter in feet. Stress is then F/A where A is the cross sectional area of the tenon, which of course varies with the chamber. You would probably come out with somwhere in the 50-75 ft lbs range, perhaps higher. For example, 50% of yield torque on a high strength 1/2" bolt is 60 ft lbs. But force is higher on the larger diameter barrel threads.
Getting back to embeddment, for those of you that haven't fallen asleep yet: Embeddment is a method to remove as many of the imperfections as possible and mate the threads together as much as possible to eliminate relaxation, thus negating the need for excessive torque. Embedement is very simple, tighten and loosen the joint to about 80% tight a dozen times of so. I do it lubricated but the idea is that is seats all imperfections so that after final torque, there is no room for movement in the joint so when you fire the rifle the joint doesn't relax and loosen up.
Another factor that negates the need for excessive torque is that rifle barrel joints seem to get tighter over time rather than looser. The need for huge action wrenches and barrel vises if for disassembly, not assembly.
So in conclusion, I do my embeddment routine and then snug it up good and tight with the action wrench. I'd guess about 40-50 ft lbs.
--Jerry
If both sets of threads are perfect 60 degree V's like you draw them on paper with no dings, gouges of imperfections, when you snug them up they will make full contact and any further tightening will be straining the metal (stretching it). In this case, the threads are 16tpi (remington) which means .062" per revolution. so those turning it 1/4 turn are/would be stretching the tenon .015" which is way beyond the yield strength of the steel.
Of course that isn't what is really happening. First the threads aren't perfect and second there are some real world issues such as lube that gets squeezed out and joint alignment issues (probably small with a good gunsmith), etc. So what most of that 1/4 turn is doing is working through all of the imperfections before you start stretching the tenon. So depending on how much turn it takes to start stretching the tenon, 1/4 turn could be anywhere from moderately tight to breaking it. So i don't like using x/y turn past snug for this application. I'm sure some guys make it work but they probably modify it based on feel and are actually doing a torque by experience method and experience almost always works.
Now to calculate a torque isn't that hard. You want to usually torque to 50% of yeild which on a quality action is probably somewhere around 75ksi for carbon steel, not sure about what type of stainless is used. Austenitic stainless is usually much less than that. The force from torquing if T=.2F/D where D is thread diameter in feet. Stress is then F/A where A is the cross sectional area of the tenon, which of course varies with the chamber. You would probably come out with somwhere in the 50-75 ft lbs range, perhaps higher. For example, 50% of yield torque on a high strength 1/2" bolt is 60 ft lbs. But force is higher on the larger diameter barrel threads.
Getting back to embeddment, for those of you that haven't fallen asleep yet: Embeddment is a method to remove as many of the imperfections as possible and mate the threads together as much as possible to eliminate relaxation, thus negating the need for excessive torque. Embedement is very simple, tighten and loosen the joint to about 80% tight a dozen times of so. I do it lubricated but the idea is that is seats all imperfections so that after final torque, there is no room for movement in the joint so when you fire the rifle the joint doesn't relax and loosen up.
Another factor that negates the need for excessive torque is that rifle barrel joints seem to get tighter over time rather than looser. The need for huge action wrenches and barrel vises if for disassembly, not assembly.
So in conclusion, I do my embeddment routine and then snug it up good and tight with the action wrench. I'd guess about 40-50 ft lbs.
--Jerry
NYM
Welcome to the forum. Hope you enjoy participating here.
What you do with Mosin-Nagants sounds fascinating.
When refitting a barrel, how far can you get the barrel into the receiver using only hand pressure? Would you have any numbers on the torque required to get back to the 27 deg. mark.?
I am also impressed with Russian made/designed rifles and would genuinely like to here more about what you do to them.
Welcome to the forum. Hope you enjoy participating here.
What you do with Mosin-Nagants sounds fascinating.
When refitting a barrel, how far can you get the barrel into the receiver using only hand pressure? Would you have any numbers on the torque required to get back to the 27 deg. mark.?
I am also impressed with Russian made/designed rifles and would genuinely like to here more about what you do to them.
50 ft/lbs is what I find keeps my barrels secure.
Achieved by means of a $40 Craftsman 1/2" torque wrench & whichever socket fits the action wrench I'm using, I've found that applying the same torque value used when I mounted my front sight bases brings them nicely back into parallel with the rear sights' elevation mechanism too.
(Folks not using match/iron sights won't find much value in that last bit.)
Achieved by means of a $40 Craftsman 1/2" torque wrench & whichever socket fits the action wrench I'm using, I've found that applying the same torque value used when I mounted my front sight bases brings them nicely back into parallel with the rear sights' elevation mechanism too.
(Folks not using match/iron sights won't find much value in that last bit.)
I'm having a hard time forming answers for some question. Below I've been called an "idiot" amongst other colorful remarks. I've heard such a wide variety of numbers it makes me wonder. The one thing no one has said - "the manufacturer recommends you tighten to ??? lbs for a secure permanent fit. Bat - Panda - Barnard and many other high dollar actions must have information that comes with them that leads you to a standard number with no variation or deviation. With what some these actions cost and the wait time to get, I would do EXACTLY what the manufacturer says to. If there is no information available - what do you do? You take apart several which I have. Then you put them back were they started. I'm not a gunsmith - I'm a machinist and I use logic and learned experience from doing. I work on one type firearm - all my tooling is specific. I make Bull Barrels which are very heavy, mine weighs 10 lbs with the muzzle brake install. My rifle weighs 18.5 now with the new CAA bipod and mount. The comment in the very first post is way off - 1/8-1/4 turn would destroy the weapon. 27 degrees is 1/13 of a radial turn. 37 million were made like this - as for accuracy - Vasily Zaytsev has 225 confirmed kills in the battle of Stalingrad and many at 1000 yd across the river.
As mentioned in a post not long ago, thread tolerances are the key to how much force it takes to secure two parts with a threaded connection.
Those Russian rifles were made to different specs than the stuff we mess with today. What worked for them (I watched 'Hook' Boutin use a 4' pipe to 'time' my NM M1's .308 barrel to the action several years back, no torque wrench was anywhere nearby) so without having someone who knows what kind of force they used and can provide a number, it's mostly a question now of what's "enough"?
With modern steels and carefully fitted threaded connections I submit 40-50 ft lbs to be adequate.
Those Russian rifles were made to different specs than the stuff we mess with today. What worked for them (I watched 'Hook' Boutin use a 4' pipe to 'time' my NM M1's .308 barrel to the action several years back, no torque wrench was anywhere nearby) so without having someone who knows what kind of force they used and can provide a number, it's mostly a question now of what's "enough"?
With modern steels and carefully fitted threaded connections I submit 40-50 ft lbs to be adequate.
carlsbad
Lions don't lose sleep over the opinions of sheep.
NYM,
You are right on to recommend doing what the manufacturer recommends. Often manufacturer recommendations are based on experimental data which takes into account all of the effects that I discussed in my post above. If the OEM says 27 degrees, that should generally work just fine. I did watch the video you linked and 200 ft lbs seems a bit excessive for a modern weapon. I don't have much experience with Mosin Nagants so I won't comment on that other than to say if that is the way it has always been done successfully, stick with it.
But it is not correct to take the experimentally determined direction for one gun and use it on another gun. 1/4 turn would be ok on some joints but not ok on other. Torque values translate from joint to joing much better.
One comment, I would use a high temp anti seize instead of motor oil. I use a nickel based anti seize. The joint can get pretty warm at times and that could be what caused the high removal torque.
So I don't recommend using 27 degrees, 1/4 turn, or any other "turn past snug" on custom threads or any other joint that hasn't been experimentally verified. Generally this type of direction is developed in the shop for those in the field to use without instrumentation.
--Jerry
You are right on to recommend doing what the manufacturer recommends. Often manufacturer recommendations are based on experimental data which takes into account all of the effects that I discussed in my post above. If the OEM says 27 degrees, that should generally work just fine. I did watch the video you linked and 200 ft lbs seems a bit excessive for a modern weapon. I don't have much experience with Mosin Nagants so I won't comment on that other than to say if that is the way it has always been done successfully, stick with it.
But it is not correct to take the experimentally determined direction for one gun and use it on another gun. 1/4 turn would be ok on some joints but not ok on other. Torque values translate from joint to joing much better.
One comment, I would use a high temp anti seize instead of motor oil. I use a nickel based anti seize. The joint can get pretty warm at times and that could be what caused the high removal torque.
So I don't recommend using 27 degrees, 1/4 turn, or any other "turn past snug" on custom threads or any other joint that hasn't been experimentally verified. Generally this type of direction is developed in the shop for those in the field to use without instrumentation.
--Jerry
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