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Rechambering revolver cylinder

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  • Rechambering revolver cylinder

    I was talking to a friend and when I mentioned that I had purchased a small mill (Grizzly G704)
    he asked me if I could rechamber 3 or 4 Ruger Blackhawk cylinders for him. The reason being that Ruger does not offer extra cylinders unless the pistol is purchased as a combo gun. Now he's done all the research and says that the various cylinders he has are capable of being rechambered to the desired calibers and he understands that the timing may not be perfect. the calibers he wants are old antique ones or ones that will make a somewhat unusual handgun. He's found a place he can rent reamers and I think I've got a way to build a fixture but I have no idea about speeds or feeds. Any suggestions?

    Thanks,
    Joe

  • #2
    Step #1 -

    Make sure your insurance premium is paid in full!

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    • #3
      Before you do this you may want to check into the local and federal laws concerning such work.

      What the mill provides, assuming you got it neatly and accurately trammed, is a machine where you KNOW that the spindle is normal to the table in all respects so the reamer runs into the chamber very axially.

      Rather low speed is needed as with most reamers. If in doubt err on the side of too slow instead of too fast. Lots of cutting oil and don't feed in any faster than you would if it were a drill bit. That last takes patience because there's no real load in the lever or through the dial or however you do the job.

      If you want it clamped down hard instead of floating then make up a long angle taper pin to fit the mouth of the existing chamber to locate the chamber. Clamp in place while the pin is locating the chamber snuggly. Pop out the locating tapered pin and swap for the reamer and ream that chamber. Swap back to the tapered locating pin and repeat for the next chamber.

      You'll want to check the run out of that pin before you trust it too. And overall this would be a good time to break out the better collets if you have them. Or at least check the runout and go buy a new collet if the runout is more than about a half thou.
      Last edited by BCRider; 12-05-2017, 02:08 AM.

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      • #4
        Depending on the source for the cylinders, there are a couple of ways to do this. If previously chambered, there might be no choice other than what BCRider has described. It will work OK, but might have timing problems. If using new, unchambered cylinders, which are available from time to time through aftermarket suppliers, the cylinder can be line bored on the existing frame and then chambered, which will address the timing problem.

        When using a chambering reamer, use low speed and lots of cutting oil. Withdraw the reamer frequently and clear of chips. It should be noted that there are reamers specifically for chambering revolvers, and they must be used, not those for rifles as a throat is required for a revolver cylinder.
        Jim H.

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        • #5
          Some good machining advice here. Ideas I may use myself.
          It's legal to build a gun as long as it's for your own use and not for sale. (see the BATF rules for full information).
          I don't think recharmbering or for that matter building from scratch a cylinder constitutes building a gun. The frame is the gun in the rules of the BATF since it has the serial number.

          If I were at all concerned about a potential lawsuit I would decline to help my "friend", not buy insurance.
          Bill
          I cut it off twice and it's still too short!

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          • #6
            What the heck is a rechamber?
            I know what countersink and counterbore means.
            Sounds like partisan lingo.

            -Doozer
            DZER

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            • #7
              For center fire I don't see that indexing would be an issue, however if rechambering for old rimfire ammo yes, Absolutely an issue.
              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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              • #8
                Originally posted by barracudajoe View Post
                I was talking to a friend and when I mentioned that I had purchased a small mill (Grizzly G704)
                he asked me if I could rechamber 3 or 4 Ruger Blackhawk cylinders for him. The reason being that Ruger does not offer extra cylinders unless the pistol is purchased as a combo gun. Now he's done all the research and says that the various cylinders he has are capable of being rechambered to the desired calibers and he understands that the timing may not be perfect. the calibers he wants are old antique ones or ones that will make a somewhat unusual handgun. He's found a place he can rent reamers and I think I've got a way to build a fixture but I have no idea about speeds or feeds. Any suggestions?

                Thanks,
                Joe
                From what I know about Ruger Backhawks, they are 44. Magnum. That's a large, high pressure cartridge. Your friend states that he understands that "the cylinder timing may not be perfect" after a rechambering job. That's a definite red flag. A poorly timed revolver will spit lead from shaved projectiles and this might even increase the chamber pressure for an instant. He doesn't say what calibers he intends, either. If they are physically larger, this could weaker the cylinder to a great extent.

                I do not know the law on working on guns, but I can imagine the legal consequences if it were to blow up after your rechamber. Unless you are a gunsmith I would run away from that job.
                Last edited by GNM109; 12-05-2017, 11:29 AM.

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                • #9
                  Rechamber means to recut the chamber, either deeper to refresh the original (a rifle with too much headspace or worn out throat), or to fit a different kind of ammunition.

                  I've done lots of them. Made 2 ea. 40 S&W out of 357, 38 Super out of 38 Special, 9mm out of 357, 44 Auto Mag out of 44 Mag, etc.
                  The best way to do this is to put the cylinder in a vise with leather or rubber padded jaws, and either turn the reamer by hand or with a cordless drill on low speed. The reamer will follow the original hole if you are careful not to put any side pressure on it. There will be no timing issues that weren't already there. It may be a good idea to put 2 or 3 empty cases in the chambers not being worked on to stabilize the extractor rotationally. Deburr all sharp edges created by the cutting action, both on the cylinder and on the extractor.

                  DO use lots of cutting oil, clean the chips often, turn the reamer slowly. DON'T reverse the reamer. If the chips get packed in the flutes, there will be circular scores on the chamber walls which can cause difficult extraction. If you reverse the reamer, it will dull the cutting edge and it won't cut properly. Once all the chambers are reamed, you can polish them with a piece of red ScotchBrite wrapped around an undersize cleaning brush.

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                  • #10
                    GNM, there's lots of Blackhawks and Convertible models out there in smaller calibers which could be re-chambered to low(er) pressure antique rounds that share the same bullet diameter as some modern cartridges. Or that might need a re-barrel along with the cylinder chambers. d

                    But of course each case would need to be looked at carefully to be sure that the entire chamber from back to front is such that the chambering reamer is going to clean out metal at all points. An oversize throat area is just as bad as a chamber doesn't support the casing correctly.

                    And a good point about the revolver reamers. It's not a deal killer if the reamers are rifle reamers. Just means that the throat would require a second proper sized standard reamer to finish the job.

                    Joe, one thing about this job. If you're not totally satisfied that your buddy is ensuring that the barrel bore is compatible with his conversion then pass on the job. For example, converting a .357Mag gun to something like .38-40 would require a change of the barrel for certain. But some folks might think that a conversion from .357 to .38 Long Colt might be OK. But with .38LC using a .361 bullet that's a LOT Of swaging down and not a proper or wise idea at all. So unless he's got someone that will match the barrel change with your cylinder work for some of the possible conversions I'd be inclined to make up some sort of excuse to not do the job. Or if he's not that great a friend just outright tell him that you don't agree with how he's wanting to do it if he's taking shortcuts or trying to put bullets out of your cylinders through improper sized barrels.

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                    • #11
                      If rechambering a cylinder to a larger bore size, the first step is to ream or bore the original chamber hole to the new bullet dia. This is because a cylinder reamer( as opposed to a barrel reamer) has a bullet dia. pilot. Cylinder reamers are commercially available in a only few popular calibers. Of course, custom reamers can be made for any cartridge. Barrel reamers can be used, but the pilots will have to be bushed up to bullet dia. if you expect them to guide the front end of the reamer.

                      RWO

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                      • #12
                        What he's after is to take a cylinder in .30 Carbine and rechamber it to .30 Luger. Another from .357 mag to
                        .357/44 Baines and another in 9mm opened up to .357 Sig. At this point I haven't verified all the dimensions but of course I would before attempting any of this. Why anyone would want a .30 Luger revolver or a .357 Sig six shooter is beyond me but Daryl loves unusual caliber/firearm combo's.

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                        • #13
                          I think the .357/44 is Bain & Davis.

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                          • #14
                            The legal aspect is that you have the frame of a gun in your shop and the owner is not there with it, then you need a FFL and must have it (the frame) logged into your bound book. If the owner stepped out as an ATF agent walked in, you could be in big trouble.

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                            • #15
                              Cylinders are not usually serial numbered and are not considered a firearm. No FFL needed to rechamber from one caliber to another. No different than changing barrels or uppers on an AR

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