Barrel step contouring

Discussion in 'Advanced Gunsmithing & Engineering' started by Someoldguy, Jul 2, 2017.

  1. Someoldguy

    Someoldguy

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    Is there any 'rhyme or reason' to where to begin and/or end the steps in a step contoured barrel? Same question regarding the diameter changes and abrupt, square steps or angled steps? I've done some searches and found little information on the subject. Thanks in advance.
     
  2. boltfluter

    boltfluter Gold $$ Contributor

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    Do you happen to have a pic of what you are trying to do?

    Thanks, Paul
     
  3. WayneShaw

    WayneShaw

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    I assume the OP wants to lighten a barrel,without tapering it. Didn't Mausers have this? I would decide on how many steps you want and what the diameter delta is, then make them even length/depth.
     
  4. Someoldguy

    Someoldguy

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    No, I'm not trying to replicate anything, and so far as I know, there isn't any other example of what I'm making. I'm building one of the DeHaas Chicopee actions, and as I have never built something like this before, I bought an unprofiled blank. My lathe bed isn't long enough to get the blank between centers, and step profiling had been suggested to me as a possible alternative.
    The reason I want to profile the blank in this case is both for appearence and weight reduction.
    Should have given more details to begin with, thanks for asking.
     
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  5. GenePoole

    GenePoole

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    How do you get an 11 thou taper per inch? Cut 11 thou off each inch. That's 5.5 thou a side. That'll clean up with a spinner and a 60 grit belt to start.

    [​IMG]

    Sorry, but I don't have a photo of the spinner work.
     
  6. IdahoCTD

    IdahoCTD Silver $$ Contributor

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    Why not set up the compound to cut .0055/inch? You can taper the barrel in segments with part in the head stock and a tail stock in the bore. The bore will be off center part way down the barrel anyway, even if it's turned on centers, so doing it like that won't matter much. Or you can mark the barrel as above and back the compound off as you get to the marks, or even gradually between marks, while power feeding it.
     
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  7. Shawnba67

    Shawnba67 Silver $$ Contributor

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    I had heard the Germans actually tested several different step lengths trying to optimize it for their 8mm no way to verify that though. I do think the step barrel is sexy though, that's reason enough.
    I would think an abrupt shoulder between steps could improve rigidity over a small tapered step. Again no way to verify.
    There is an article in rifle magazine(I think) the guy cuts a sporter contour in small steps. He would measure every .1 and had corresponding measurements for it. If you do this they come out looking like a real contour with minimal belt sanding.
     
  8. Someoldguy

    Someoldguy

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    That is what I presumed the German's did, however, I've not been able to find any confirming information on the subject. Given what was going on, I can't decide if there was time for testing or not. But given Mauser was able to conceptualize the bolt action, it seems reasonable to assume step profiling was a cake walk. (?)

    Either way, I think step profiling with a 90 degree step is the profile I'm going to use. As you stated, it will be unlike any other.
     
  9. X Ring Accuracy

    X Ring Accuracy Site $$ Sponsor

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    Just cut it the way it looks good to you. More time reading this than doing it :D
     
  10. rayjay

    rayjay Silver $$ Contributor

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    Here's a RF bbl I did to see if I could create a constantly tapering bore . Didn't shoot good enough before or after :)

    [​IMG]
     
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  11. Someoldguy

    Someoldguy

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    Is that a 'reverse taper', or whatever the correct term is? Or does the picture just make it appear so? I'd never thought about that approach.
    Interesting!
     
  12. rayjay

    rayjay Silver $$ Contributor

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    Reverse step. Hard to call that mess a taper. It looks like it telescopes :)
     

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