Kirby Shawn and other Smiths

Discussion in 'Gunsmithing' started by lerch, Dec 10, 2007.

  1. lerch

    lerch <strong>SPONSOR</strong>

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    I just had a customer ask me this and i was completly stumped for a answer. When you torque a bbl onto a reciever how hard to you do it???? is there a standard in/lb rating like there is on reciever screws and stuff???? i just realized i had no idea how you go about attaching this stuff so i figured i would ask. I kinda feel dumb now but you only learn one way.:D:D

    thank
    steve
     
  2. specweldtom

    specweldtom Well-Known Member

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    Lerch, for tenons 1" to 1.1" major diameter, with 5/8" of threads or more I make up at 100 - 125 ft/lbs.

    I can't remember why I decided on that, though! Tom
     

  3. James Jones

    James Jones Well-Known Member

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    I have never used a torque wrench but compairing it to how hard i torque my wheels on my truck i'd say maybe 75-80ft-lbs that with justa little dap of blue loctite and I've never heard of a problem with any of my guns. Thats with a regular rem 700 reciever with the threades cut to 1.075" which is .013" over factory generaly. I think that 60ft-lbs would be fine though. I have heard of some guys leaning over on a 24" long 1/2" breaker bar to tighten them probably around 200+lbs !!! I just don't see the point unless the barrel has a backwards twist that could cause it to shoot loose
     
  4. 257speed

    257speed Well-Known Member

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    In accuraacy facts, Vaughn settled on 125lbs. I don't know that I ever tighten them that much. The extremely accurate bench rest switch barrel guns are probably only using 40-50lbs, so I sure don't think it has to be too tight.
     
  5. koginam

    koginam Well-Known Member

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    I have never used a torque wrench either, I have just gone tight and then an 1/8 of a turn more never had a barrel come off or get lose yet. And like 257speed I know my switch barrels are not over 50# and they shoot fine.
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I have played with this a little bit.

    I feel the determining factor to some degree is the quality of the thread fit. WHen you accurize a receiver, you recut the threads using a one half of a matched set of thread cutters. One does the internal receiver threads, the other does the barrel threads.

    Using these matched sets of thread cutters, you can get a thread fit that is amazingly quality. When your machining the threads, you can have the threads be to tight to start the barrel and then, just by taking a 1 thou cut(1/2 thou but off both sides 1 thou total cut) and the receiver will thread on all the way to the barrel shoulder.

    With a thread quality like this, the amount you torque the barrel to is much less important.

    Many 100 and 200 yard BR shooters have their barrels torque on very ligthly, in fact I have testes a 6mm BR barrel that was torqued to only 20 ft/lbs and it shot AMAZINGLY well and did so for well over 300 rounds.

    On the other end of the scale, I have tried this with my 7mm AM and the 200 gr ULD RBBT loaded to 3300 fps. The barrel was a 30" #7 contour Lilja with a 1-7 twist. I indexed the barrel and lug so that I could tell if the barrel turned at all. After four firings the barrel did start to turn simply from the torque generated by this extreme round, heavy bullet and fast twist.

    I do not use a torque wrench anymore either, just go by feel. I would guess it would be around 70 to 80 ft/lbs on my larger rifles that will produce alot of barrel torque. I would say its pretty much the same for the smaller ones as well as they are all pretty much the same.

    What is needed to keep a barrel in one place, on a factory rifle, I would say they would need more because of the poor thread fit. Some factory barrels are put on with well over 150 ft/lbs of torque which is not needed in any way. Other are screwed on with thread locker as well to hold them in place.

    The varation in barrel torque from one factory rifle to another is frankly amazing to me. One barrel will pretty much fall off while another one I will need my 6 foot cheater bar to break it loose. May be a big reason that factory rifles are so inconsistant from one to another.

    I would say anything over 60 ft/lbs with a factory chambering would keep a barrel in one place pretty easy but 70-80 would be better in my opinion. I would doubt I ever get near 100 ft/lbs.

    Kirby Allen(50)
     
  7. daveosok

    daveosok Guest

    I've gone as high as 185 using a torque wrench and as tight as a 2 foot cheater bar would take it to guessing 80 to 100 ft lbs.

    I read indepth in Vaughns book about torque values but havent really applied any tests to it just torque them down tight 80 to 100 ft lbs would be good enough.
     
  8. Black Diamond 408

    Black Diamond 408 Well-Known Member

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    Dave,
    Where you been hiding??????
     
  9. HeskethPritchard

    HeskethPritchard Well-Known Member

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    I thought I'd read somewhere it was 65ft/lbs for the stock and I think 25ft/lbs for the scope???
     
  10. Shawn Carlock

    Shawn Carlock Sponsor

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    I hope you read IN/LBS!!!!
     
  11. lerch

    lerch <strong>SPONSOR</strong>

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    I was about to say the same thing Shawn!!


    Thanks for all guys, it was just a question i was asked and i realized i had no idea, thanks for the info

    steve