Threading and crowning with a steady

Discussion in 'Gunsmithing' started by zoeper, Jul 3, 2010.

  1. zoeper

    zoeper Well-Known Member

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    Feb 20, 2008
    I would like to re-crown and thread one of my barrels and could do with some advice.
    My lathe only passes 3/4" through the headstock so i can not crown using a 4jaw and a spider on the back of the spindle.
    I want to clamp the chamber end in the 4jaw and run the muzzle end in a steady. doing it this way would make it impossible to set up concentric to the bore as opposed to concentric to the outside of the barrel.

    I was thinking that it might be better to set up with a tailstock center and cut the thread and shoulder first as well as Crowning the outer part of the muzzle.
    I can then fit a thread protector and cut the OD of the thread protector) smooth while running between centers and then do a recessed crown while running the steady on the thread protector.

    Any advice or comments apreciated
    Pieter
     
  2. J E Custom

    J E Custom Well-Known Member

    Messages:
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    Jul 29, 2004

    Get a range rod from PT&G for your bore Dia. and carefully insert it in the muzzle end of
    the barrel and using the Steady rest Indicate it on the range rod until it is true. This way
    your crown and threads are off the same center line and accurate.

    After it is dialed in remove the range rod and you are ready to go.

    Do the crown last so if you need to shorten the tenon to get the proper fit in the brake.

    Again; be very careful any time you place anything in the muzzle end of the barrel and
    dont put any force on the range rod.

    Hope this helps.

    J E CUSTOM
     

  3. zoeper

    zoeper Well-Known Member

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    Feb 20, 2008
    Thanks for the advice JE, I would propbably have to get a set of range rods since i have no way of measuring the barrel inside.
    My biggest concern at the moment is if the od and ID of the barrel is not concentric, i would not be able to do anything more to correct it if i have to run in the steady as opposed to through the spindle..... Unless i make a smaller version of the action truing jig to clamp around the muzzle and correct any riunout that way.
    I am busy making a barrel vice at the moment and as soon as i have the barrel off i will do some testing.
     
  4. Fitch

    Fitch Well-Known Member

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    Aug 5, 2009
    I've not chambered a barrel in the steady rest, but if I was going to do it, this is how I'd do it assuming I was starting with a new barrel blank fresh from the barrel manufacturer:

    The new barrel blank should already have a 60 degree cone in the bore at the muzzle and breech. Install the barrel between centers with the muzzle on the tailstock end and machine the OD of 3/4" or so of the muzzle round which will also be concentric with the bore. Reverse the barrel in the lathe and take a light cut on the breech end to make the OD concentric with the bore.

    Cut the usual inch off the breech of the barrel blank to get past the part of the bore that is probably oversize due to lapping.

    When you put the breech in the steady, you can use your 4J to hold the muzzle and use this newly machined surface to center it in the chuck which will also center the bore.

    Then center the breech using a range rod as Kirby suggests. You will only need one range rod per caliber, but you may need several bushings depending on the actual bore size.

    When the machine work (tenon and chamber) on the breech of the barrel is completed, make a thread protector as you suggest.

    Saw the muzzle end off past the trued surface, reverse the barrel in the lathe, center the thread protector in the 4J, use the range rod to centered the muzzle in the steady rest, then machine the crown, install a muzzle brake, etc.

    Fitch