Barrel torque question

A

Andy Cross

Guest
I am in the process of building a new LV/HV switch barrel BR rifle. The one question I have is how many foot pounds of torque should barrels be tensioned up to. Of those who I see using this system I have yet to see any one use a torque wrench to tighten up the barrel. As a physicists I know this could have a significant effect on the looseness of a barrel when being loaded during firing a round.
Andy.
 
Lets open this can of worms again. Can of worms? Yep, since there are many opinions as to what is optimum tightness.
I tighten mine to about 100-125 ft/lb. I have watched Greg Walley and George Kelbly tighten barrels and I feel my 100-125 ft/lb is about right.

A big caution here, especially on SS actions and SS barrels always use plenty of a good thread lube.
 
Well now that you mention it

Well if you really want to know the torque level on a jar of peanut butter you would have to ask the engineer at the plant where it was made. There would be a number that has to be applied to meet consumable products standards. I don't need to know that to secure a barrel to an action. But when you haven't had to do that task before it helps to know what torque level is required so you can get a feel for it. Get it.
Andy.
 
I was told to use 60 lbs but last time I put on the barrel it just didnt feel like enough so I moved it up to 70 lbs.
I have had the barrels on and off of this gun several times. Last season I put the barrel on with 60 lbs and it stayed on for 1000 rounds.
Sure took more than 60lbs to take off. Yes I used antisieze.
I dont have any reasoning for the 60 lbs other than thats what I was told and it seemed to work. I am anxiously waiting to hear from others.
 
Tell you what, why don't you test your assumption and get back to us? I think that as long as you barrel does not come loose while you are shooting it, that you may not see the difference that you assume will be there. Personally, I use one of the Kelbly's, rear entry T handle wrenches, and I put my barrels on big fellow, hands flush with the ends of the T handle tight, and use Pro-Shot Gold on the threads and shoulder, which I switched to after becoming tired of the Permatex mess.
 
Is there really any difference, in elongation, between 60 ft/lbs. or 120 ft/lbs. of torque to make a significant difference?
 
Andy Cross said:
I am in the process of building a new LV/HV switch barrel BR rifle. The one question I have is how many foot pounds of torque should barrels be tensioned up to. Of those who I see using this system I have yet to see any one use a torque wrench to tighten up the barrel. As a physicists I know this could have a significant effect on the looseness of a barrel when being loaded during firing a round.
Andy.
Click to expand...

Andy,
Pm sent
 
What would be the minimum torque to prevent the brass to grow and move the neck forward? Or this dont happens?
 
Read it

Yup,
I have this book in my collection. Read it twice over the years. Much of what is in it I agree with based on that data obtained and how the laws of physics apply to it. Some of the testing methods I don't agree with. The part relating to thread pre loads, distribution of preload across thread surface areas and ramping threads vs vee threads pretty accurate I think.

However torquing up a thread to a desired preload isn't something that can be guessed by leaning on a wrench. Yet I haven't seen anyone at the range using a torque wrench to determine how much force they are applying even though they may tell you that they torque their barrel to X. Sure you will get a feel for it after a few times but you have to know what that number feels like. Do any of the manufacturers making barrel wrenches incorporate a torque preset device in any of their wrenches or is it something we have to adapt.
Andy
 
the automotive industry

has moved on to degrees of rotation as there are to many variables to truly get a consistent torque with a force guage.
 
Personally, I use one of the Kelbly's, rear entry T handle wrenches, and I put my barrels on big fellow, hands flush with the ends of the T handle tight, and use Pro-Shot Gold on the threads and shoulder, which I switched to after becoming tired of the Permatex mess.
Click to expand...

Ditto...

I have used 60-80 ft/lbs for years and NEVER thought "my" barrels tension affected accuracy... Never came loose, kept tension... Turnes out that I can put "my" desired tension by a light rap on the wrench to set the threads.. Works well and that same rap (may be a touch more) on the wrench easily breaks the barrel loose... Use plenty of anti-sieze.

I believe in taking the scope off during barrel switch'n (internal adjustable scopes in particular).... These things don't need any additional stresses..!

Andy, like everything in this sport, you'll over time get a "feel for it, what works for you"...

cale
 
As a side note, I always find it a bit funny when fellows calculate and research something that would be safe and easy to test. Years ago, after I explained something related to reloading that I had worked out on my own, thoroughly tested, and explained in detail to a friend, who was having a problem that related, and the first thing out of his mouth was "What's your reference?" as if some joker writing about it in a magazine article would automatically be a superior source on the subject. Calculations can be impressive in their complexity, but if the math is not applied correctly, the results will not depict what happens in the real world. Similarly, test results that come from experiments that differed significantly from the application in question should probably not be taken as immutable truths. A good part of my slight formal exposure to engineering took place in a strength of materials class, where destructive testing played an important role. In the real world, this sort of testing is widely employed...for good reason. IMO, with the usual disclaimers about safety, if you want to know what will happen, why not give it a try?
 
I know this is anecdotal, and does not follow the scientific method at all; but I was changing a barrel at the SS a few years ago and Dwight Scott walked by just as I was finishing tightening it. At that time I was using about 50-60 #ft., and I asked Dwight if he thought it was tight enough. He said that he prefered his tighter. With that I used what would probably measure 100-125 #ft. He said that is what he preferred. Although I have a torgue wrench, I don't use it. I do try for at least 100#ft. each barrel change, and it seems that my gun has shot better since I went to more torgue. Boyd, I guess my reference is one of the best gunsmiths in the USA. Good shooting...James
 
On the subject of threads

I know without question that the thread type, turns per inch, depth and pitch can make quite a difference in the degree of preload that can be achieved. In Vaughn's book he makes mention of a ramping thread for a barrel as opposed to a standard V type gas thread and that it was probably a better choice for this application. Do any rifle smiths use this type of thread. Has anyone on the group had any experience with this type of thread. I would be interested in hearing any about this from either a theoretical or practical point of view.
Andy.
 
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