How much torque on barrels

[NYM]

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

Thank you Carlsbad, your the first person who's spoken with the right words "do what the manufacturer says". Some of the numbers here have a 100% spread 40-80 foot pounds -- the deviation is ridicules. The video you watched is not the only material I've studied. I've read 100's of threads on re barreling the Mosin with the UK-59 barrel before I even tried mine. The ones I respected the most were ones written by military personal that had the help from there armories on base. With no real factory specs I put them back the way I found them. I will not confess to the number of these I've put together cause of legal reasons -- but if you counted fingers and toes - you'd be a freak. Only one complaint in all my builds and I've taken mine apart a few times to add muzzle brake threads. Never had a pulled or distorted thread in any of my own. I have to pull the barrel off my wifes rifle to add a brake. At that time I will do a complete check of a mating surfaces for damage.

 

[BigDMT]

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.

So you are not a gunsmith.
You only have standard knowledge to work on one type of firearm which is completely outdated.
And you are arguing with some of the top competition shooters and gunsmiths in the world? ...

Not trying to be a jerk. I am only a garage gun warrior myself. But I am having a hard time finding credibility on your side of the table.

 

[Erik Cortina]

BigDMT, the following post should clear things up for you a little.

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...

NYM, welcome to the forum. We appreciate your input, but the name of this site is "Accurate Shooter" and you have to understand that for just about any of us 1.5 MOA at 1,000 yards is recurve bow accuracy.

There are many of us on this site that understand accuracy and how to put a barrel on an action properly. How do we know it's right? Well, they shoot like God made them, that's how we know! There are also some that think they know, but they don't. Most of us put ourselves and our guns against the best of the best in the Nation, and every now and then, the best in the World. That is where we really find out how good we and our equipment is. One last thing, I don't think you will find any of the action you use for your builds winning any major matches soon.

 

[Tozguy]

NYM,
I hope that we will cut you some slack. This forum is not just for the elite of top level competition.
Considering the number of members here and the variety of interests, there is a place for you I am sure.
It can get really fun when people check their attitude and name calling at the door.

 

[NateHaler]

If you keep calling firearms/rifles "weapons", then I'm gonna start calling you unpleasant names.

Is a fist a weapon? Yes. Ditto a knife, a brick, your car, a book of matches, a hammer, Hillary Clinton's tongue, a horse trough filled with water, and so on.

Does it do any good to go to the Ford dealer and say "I'd like to buy a weapon"? No.

You're harming the cause. Yeah, yeah, all of you who justify this say "blah blah it comes from LEO or military training". Whatever. Get with the program and call our implements what they are: rifles, shotguns, handguns, whatever.

Think about that the next time you stroke your child's face with your "stranglers" (hands) or ask the waitress at Denny's for a weapon so you can cut your ham slice.

 

[NYM]

See ya -- I didn't realize at what altitude I was flying.
This is ACCURATE SHOOTING for $1500.00. I knew there was a reason I never joined earlier. Sure are a disappointing lot here.

 

[BigDMT]

See ya -- I didn't realize at what altitude I was flying.
This is ACCURATE SHOOTING for $1500.00. I knew there was a reason I never joined earlier. Sure are a disappointing lot here.

You opened the flood gates yourself sir.

I've been told many times that the way I do things, or how I thought something should be done is wrong. I will debate a bit on some things, but I try to keep an open mind as well by never being too proud to learn from others. And you know what?... A lot of times I will try it someone else's way and son of a gun if it don't turn out to work better. That's not always the case, but I think you know what I mean...

Basically I am saying, try not to be quite so bullheaded and egotistical when some of the best gunsmiths in the world are trying to show you the error of your ways. Just take it with a grain of salt and move on. New members are always welcome even if they do things differently

 

[butchlambert]

NYM,
If you search the archives, you will see I have given BigDMT a hard time in the past. We were able to put that behind us. Remember that on the internet you can't see a person's facial features or hear their tone of voice. Some of our post are abrupt without meaning to be. Just hang around and read the threads and you will get a better feel for the people on the forum.
OK, I tighten my barrels to the shoulder and then tighten them with my 2' action wrench, be it a Remington, Bat, Stiller, Panda, Farley, or whatever. I also do that on my Mauser customs. Is this correct, I don't know but it works for me.

 

[NateHaler]

See ya -- I didn't realize at what altitude I was flying.
This is ACCURATE SHOOTING for $1500.00. I knew there was a reason I never joined earlier. Sure are a disappointing lot here.

awww, people can't hurt your feelings unless you let them. and all shooters on every forum know that a winking emoticon is like Bactine -- it takes the sting out of the booboo.

When you post on a topic, you're likely to get feedback. Some of it you may not like. That's the risk. If you want somebody to tell you what you want to hear, then pay them, or watch politicians of your party on TV (i.e. pay them, like I said).

 

[Grimstod]

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

Really good post. I am going to try your formula in a few of my caculators. I am really curious to see what I will get. I will share my results here.

 

[carlsbad]

If you need any help with the formula, just send me a PM. I'll probably do some calculating too when I have some time. --Jerry

 

[Randfal]

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.

I'd say there must have been lots of targets. Happens to me sometimes too, when I get in a good prairie dog town. ;D Last time I checked, there were lots of extra Germans in Stalingrad round about that time. Sorry, I couldn't resist!

 

[Randfal]

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

Yeah, what he said.

 

[Randfal]

This has been a fun thread to read thru. That's what makes this site great. Lots of opinions to pick from. I personaly think 200# is crazy. I've been to Eastern Europe and have seen WWII era Soviet tanks and other equipment first hand and they are some of the crudest things I've ever seen. I won't knock some Chinese junk until you've seen 1942 Soviet war production weapons. But hey, they made it work and made it work fast to stay in the game. My hats off to them for it. So, I don't find it hard to believe that some Russian factory worker wasn't reefing on the end of a wrench extension in some frozen factory being screamed at to get it tight. It was probably women or someone who wasn't fit enough to be on the front lines doing it, since the men were on the battlefield. And with 37 million being produced, I imagine the quality control wasn't exactly up to ISO9001 specs. As crude as some of the "machined" parts were that I've seen, I imagine that it probably took 200ft/lbs+ to get most of them screwed together! Doesn't mean it was right.

For the record, I'm in the lightly anti-seized 30-60ft/lb division. I agree with the embedment theory also, been there and done that when needed.

 

[shortgrass]

I think it needs to be taken into account that the Mosin was made under war time pressure with tools we consider to be ancient and crude, to say the least. I'd seriously wonder if those barrels were threaded with a self opening die head, or single point cutter. I'd, also, suspect the tolerances provided were one the 'loose' side. Same goes for the receiver, was it 'taped', and if it was how close in exact size was the next tap. Those that manufactured the Mosin weren't known for their "high tech" skills. "Just get the freakin' thing on there, put a witness mark and sights on it, assemble the rest of it and ship it!". Shear numbers is what defeated the German army, that and an insane German leader. Accurate rifles of today are made in a much different way with tools that would have been unthinkable when the Mosin was made. Better tools, better materials, better means of measurement and NO war time pressure to just get it out the door. $1500? Today, that'll barely buy a bench rest quality action & barrel. It'll barely buy the components to build a nice hunting rifle. As for a machinist being the same as a gunsmith, if that was the case gunsmiths wouldn't have such a back-log, good gunsmiths, anyway. There'd be plenty to satisfy the needs. There's much more to being a gunsmith than just possessing good machining skills. If you're the machinist you claim to be, NYM, chuck that barrel up and dial it in and make some skim cuts on the shoulder so that 40-60lbs puts the sights in the proper position, adjust the tenon for length so the bolt doesn't hit it and check the head space. Now, fire it for accuracy and let us know what the results are. Lining witness marks up just to say they're lined up, with excessive torque, just doesn't make sense.

 

[Grimstod]

Would this interactive caculator give a valid answer?

http://www.futek.com/boltcalc.aspx

 

[Patch700]

I'm a physicist/mechanical engineer with a lot of experience in threaded joints.

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

Jerry , would you agree that applying the various types of thread lubricants mentioned in this topic (anti-seize in particular ) OTHER than light oil would have a drastic and negative effect on the actual clamp force achieved at a given torque value?

I have done a bit of fail testing and to be quite honest , I personally would not advocate the use of a paste such as anti-seize on anything that was required to have a given amount of clamp force relative to a torque value with respect to a threaded joint , IE: torqueing an action to 55 Ft\Lbs or whatever the case may be.

Thoughts? I'm not interested in whether or not somebodies brothers uncle has been using it with success for the last 46 years with superb results... Just facts.

 

[butchlambert]

I use synthetic bicycle wheel bearing grease. I do not like anti seize. It works for me.

 

[dakor]

I showed this to a gentleman that questioned the amount of torque I was using on a barrel and using anti seize on the threads. I took a Remington action screwed it onto the barrel and just snugged it by hand very lightly and told him to take the action off by hand. He tried and tried but could not break it free by hand and is not a weak man by any means. So unless you are a silverback gorilla as long as your shoulder is square at 40 lbs of torque you are not getting that barrel off without tools and recoil is not going to make it come loose my lightweight 375 Rum has proven that.

 

[Syncrowave]

I would never do something like this myself. It's just bad bad bad.

At least he didn't use the plasma cutter.