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  • Barrel Bushing

    I have a barrel that I was threading 1-1/16+.010” and something happened that messed up the threads.
    I would like to wipe out the threads and make a bushing to be able to restore the threads to 1-1/16+.010.
    Any ideas?
    My machinist instructor did it successfully but he has passed a while ago.

  • #2
    Im assuming you are talking about Pipe not a gun barrel.
    Beaver County Alberta Canada

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    • #3
      Originally posted by redlee View Post
      Im assuming you are talking about Pipe not a gun barrel.
      No, it is a gun barrel, my machine tool instructor did gunsmithing and told me that he had done it but he has long since passed, so I can’t ask him how he did it!

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      • #4
        Undercut and thread the barrel to a smaller thread size.

        Make a bushing of larger diameter to fit the new threads.

        Cut the bushing to the thread originally intended.

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        • #5
          +1 for what Kev74 said!
          In addition I would green loctite the bushing to the barrel. In the future you do not want the bushing to stay in the action when the barrel is removed.
          Bob

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          • #6
            I know to undersize the barrel!
            I am trying to figure out what size thread to use on the barrel and still have enough meat on the bushing to thread it 1-1/16-16 tpi!

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            • #7
              I would recommend 3/4-16 or 7/8-14 to thread the barrel, be sure to single point the threads. Make the bushing first, oversize the OD so it can be threaded on the barrel in case the internal axis is off a bit. Thread the inside of the bushing first single point it first then finish the cutting with a tap. Test fit the male threads with the finished bushing, try for a close fit to the female threads You can finish the 3/4" threads on the barrel stub with a die expanded a bit to get close fit.

              Note I am a armature machinist, I bow to someone with more experience. I have done this once and it worked.

              Steve

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              • #8
                Depending on how much meat you have left you could try filling in the bad threads with silver solder and recut to the proper size.

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                • #9
                  Originally posted by Steve Steven View Post
                  I would recommend 3/4-16 or 7/8-14 to thread the barrel, be sure to single point the threads. Make the bushing first, oversize the OD so it can be threaded on the barrel in case the internal axis is off a bit. Thread the inside of the bushing first single point it first then finish the cutting with a tap. Test fit the male threads with the finished bushing, try for a close fit to the female threads You can finish the 3/4" threads on the barrel stub with a die expanded a bit to get close fit.

                  Note I am a armature machinist, I bow to someone with more experience. I have done this once and it worked.

                  Steve
                  I talked with a friend that is an excellent machinist and he suggested 3/4 fine thread, 7/8 would make the bushing too small.

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                  • #10
                    Originally posted by aliva View Post
                    Depending on how much meat you have left you could try filling in the bad threads with silver solder and recut to the proper size.
                    the barrel is stainless steel. Will silver solder stick to stainless?

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                    • #11
                      Can you move the tenon forward?

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                      • #12
                        Originally posted by deltaenterprizes View Post
                        the barrel is stainless steel. Will silver solder stick to stainless?
                        No need to solder it. Torque to spec should hold the bushing but I would either use red Loctite, or that Black Max adhesive I hear they use for front sights. A friend of mine did this on a .308 barrel in order to reuse it and it shot 1/2 moa when done. No problem as long as there is enough wall around the chamber and sufficient wall strength in the bushing.

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                        • #13
                          Originally posted by Sleddog View Post
                          Can you move the tenon forward?
                          I could but it sure would look funny in the stock!

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                          • #14
                            You need to think outside the box as far as threads. You want to maintain maximum diameter around the chamber and make a true bushing with a uniform wall. An .0675 wall will reduce your original barrel OD by .135 . So think in terms of a 15/16-16 thread. You can find specs for that odd size.

                            Make a bushing with a 1.25 OD and an ID for the minor diameter of the 15/16-16 thread spec and the length you need. You want extra OD at this point so the bushing doesn’t collapse in the chuck while threading it.

                            Single point a practice/gage plug to the proper 15/16-16 specs. Now cut the internal bushing threads so the practice plug just fits into the internals.
                            Set up the barrel, turn to .9375 and single point 15/16-16 until the internally threaded bushing blank just fits over the new threads on the barrel.
                            Use green Loctite or Acraglass on the threads and tighten the bushing on with a pipe wrench.
                            Turn the OD to 1.0725 and take a face cut on the chamber end so the bushing and barrel match.

                            Now the tricky part...Looking at the faced end of the barrel/bushing combo, find the thread start and you need your new external barrel thread to run along the same contour of the internal bushing thread, as closely as possible, so your peaks and valleys maintain the consistent wall thickness. This way when you tighten the barrel into the action all the thread forms will deform uniformly.

                            With the nuts engaged, maneuver your cross slide and compound to set your point were it will be in the correct orientation to run along the matching internal profile, set your dials and cut the external thread to your action fit.
                            Last edited by Tim The Grim; 02-11-2021, 10:30 PM.
                            Illigitimi non Carborundum 😎
                            9X49 Birmingham Mill, Reid Model 2C Grinder, 13x40 ENCO GH Lathe, 6X18 Craftsman lathe, Sherline CNC mill, Eastwood TIG200 AC/DC and lots of stuff from 30+ years in the trade and 15.5 in refinery unit operations. Now retired. El Paso, TX

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                            • #15
                              Originally posted by Tim The Grim View Post
                              You need to think outside the box as far as threads. You want to maintain maximum diameter around the chamber and make a true bushing with a uniform wall. An .0675 wall will reduce your original barrel OD by .135 . So think in terms of a 15/16-16 thread. You can find specs for that odd size.

                              Make a bushing with a 1.25 OD and an ID for the minor diameter of the 15/16-16 thread spec and the length you need. You want extra OD at this point so the bushing doesn’t collapse in the chuck while threading it.

                              Single point a practice/gage plug to the proper 15/16-16 specs. Now cut the internal bushing threads so the practice plug just fits into the internals.
                              Set up the barrel, turn to .9375 and single point 15/16-16 until the internally threaded bushing blank just fits over the new threads on the barrel.
                              Use green Loctite or Acraglass on the threads and tighten the bushing on with a pipe wrench.
                              Turn the OD to 1.0725 and take a face cut on the chamber end so the bushing and barrel match.

                              Now the tricky part...Looking at the faced end of the barrel/bushing combo, find the thread start and you need your new external barrel thread to run along the same contour of the internal bushing thread, as closely as possible, so your peaks and valleys maintain the consistent wall thickness. This way when you tighten the barrel into the action all the thread forms will deform uniformly.

                              With the nuts engaged, maneuver your cross slide and compound to set your point were it will be in the correct orientation to run along the matching internal profile, set your dials and cut the external thread to your action fit.
                              Thanks for the help!

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