chucking tapered brass?

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  • hal9000
    Senior Member
    • Apr 2012
    • 116

    chucking tapered brass?

    Hi all,

    I just inherited a vintage rifle in a discontinued caliber (Rigby 350 Magnum), and while brass is available from one or two custom manufacturers, it's relatively pricey, and that gives me an excuse to try making my own cases. From what I've read, .375 belted cases can be converted, but it involves turning an extractor groove into them on a lathe.

    Since they are tapered cases, I'm at a loss regarding the best way to hold them in the headstock. The only Idea I have would be to use a chamber reamer to machine an emergency collet to custom fit the case... But the reamer is going to be expensive and hard to find as well which kind of negates the whole purpose.

    Is there an easier way that I'm not seeing?

    Thanks
    Last edited by hal9000; 07-29-2014, 05:08 PM.
  • oldstarfire
    Member
    • Mar 2010
    • 76

    #2
    Will go out on a limb, But in case I have not understood fully.......
    1. Decap the brass
    2. Make, and insert, a rod that fits the neck snugly. (Bullet diameter)
    3. Chuck the case and rod in a 3 (or 4?) jaw chuck
    4. Support the outer end with a live center in the primer pocket.
    5. Carefully machine the required groove.
    Might work?

    Comment

    • achtanelion
      Senior Member
      • Jun 2011
      • 446

      #3
      I'd suggest chucking a bit of steel and turning a spud the diameter of the primer pocket. Them place the case on the spud and run a live centre into the mouth, tight enough to grip, not enough to (badly) bell the mouths. Take light cuts, and you can swap cases without turning off the lathe. 100 45 colt to 450 Adams (thin the rims and trim to less than half length) took me just over 1/2 hour.

      Comment

      • KJ1I
        Senior Member
        • Jun 2013
        • 924

        #4
        I'd kind of combine both methods. Turn a mandril to snugly fit the case mouth and long enough to reach the case head. I'd turn a short stub to fit into the flash hole. Then turn another to fit into the primer hole. Chuck the 1st into the headstock, the second into a tailstock chuck. Then turn the belt off a Holland & Holland 375 case.

        Also, are you sure it's a 350 Rigby Magnum, and not a 350 Rigby or 350 Number 2 Rigby. Each takes a different starter case.
        Last edited by KJ1I; 07-26-2014, 10:28 PM. Reason: Added also
        Kevin

        More tools than sense.

        Comment

        • gzig5
          Senior Member
          • May 2005
          • 1223

          #5
          Take a look at how the Wilson case trimming tools work. http://www.youtube.com/watch?v=_Tbx7p0oRcc They use a bushing cut to the body taper to hold the case. I would either make the bushing in the lathe and match the taper using the compound, or buy the Wilson holder for the parent case and dial the bore in on the four-jaw. The Wilson holder may need to be shortened, I don't know how far out the belt will be. A chamber reamer could be rented as well for about $30. Once the case is in the holder, turn the belt off with a couple light passes and dress with fine crocus cloth if desired. Then use a rod through the spindle to knock the case out. Other options are to grab the base with a drill chuck in the tail stock and pull it out, or use a shellholder in the drill chuck to pull it out. I prefer holding on the outside of the body instead of the neck/primer pocket because I think the belt will be more concentric to the case body and primer holes rarely are perfectly centered. I'd put money down that this is the method the custom brass makers use.

          Comment

          • andywander
            Senior Member
            • Dec 2012
            • 615

            #6
            Center up a sizing die in your 4-jaw, push the case in, and then apply pressure with your tailstock live center into the primer cavity.

            Comment

            • Toolguy
              Senior Member
              • Jan 2010
              • 6666

              #7
              I would use an emergency 5C collet, bored to the taper of the case body. With a collet stop and a lever collet closer you can put the cases in and take them out in about a second each without ever turning off the lathe. The cases will be held concentric and very securely and always the same length.
              The 5C emergency collets come in soft steel, brass and nylon. Take your pick.
              Kansas City area

              Comment

              • hal9000
                Senior Member
                • Apr 2012
                • 116

                #8
                Thanks guys. As usual I hadn't taken the time to actually think things through before I asked and came up with a few of those ideas after I asked... The gun specific forum I'm a member of recommended a few more as well. Anyway, none of it will matter until (unless) I get some appropriate parent brass.

                Kevin, it's definitely the rimless .350 magnum. No question about that. I like the full length mandrel idea. I've never messed with holding work by friction fit only. Might be fun to try out.

                Gzig5, if you know of a place that has Rigby .350 reamers to rent at any price I'd like to know about it. This cartridge is pretty obsolete. Someone else recommended a wilson style holder as well. Since they appear to make them to order it might be possible to just order one from them. I haven't ruled that idea out, but would kind of prefer something I could do myself instead of relying on others.

                Andywander, I don't even have loading dies yet. I'm waiting on a guy who has a set to sell, but is in the middle of moving to a new house. That's not too different from the wilson shell holder in theory either. I'd just want to build a thread protector before chucking the die up. Great idea though.

                Thanks again guys. I've gone from no ideas to almost too many to choose from.

                Oh by the way, I just noticed the typo in the title. My bad!

                Comment

                • Rustybolt
                  Senior Member
                  • Jul 2002
                  • 4416

                  #9
                  If you have the taper per foot you could use the taper attachment on your lathe or the lathe of someone witha taper attachment and bore out some bushings. I've done this for my BIL who makes his own pool Qs.

                  Comment

                  • hal9000
                    Senior Member
                    • Apr 2012
                    • 116

                    #10
                    Would make a good excuse to build a taper attachment since I don't have one... Oh how the simple projects can lead to so many other things!

                    Comment

                    • Rustybolt
                      Senior Member
                      • Jul 2002
                      • 4416

                      #11
                      Originally posted by hal9000 View Post
                      Would make a good excuse to build a taper attachment since I don't have one... Oh how the simple projects can lead to so many other things!

                      Or do what i did originally. futz around with the top slide until I got the angle right. The bushing doesn't have to be full length.

                      Comment

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