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Boring a reloading die (how to make the neck loose?)

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  • Boring a reloading die (how to make the neck loose?)

    I'm making a reloading die, full length resizing. I have ordered the PTG die reamer.

    One aspect I would like to do is actually not resize the neck, I would like to leave that as is to SAAMI spec. The reason is the die needs to hold the case body tight, and the neck snug (but not loose).

    The die will be used to trim the cases, it will be neck sized after the trim, I'd like not to overwork the neck.

    These are 223 and 308 cartridges. Any recommendations on how to go about this?

    The die is soft metal (aluminum, not a die blank). My thought is to ream it using the die reamer as normal, and then use a coarse lapping compound and a buffing wheel to open up the neck area a little.

    Thanks, Caesar.

  • #2
    Your idea of using a reamer/compound sounds fine, however,
    If you are referring to trimming the overall length that must be done after neck sizing as neck sizing is usually where the length is gained.



    • #3
      What Ken said is true. The neck length grows after the resizing. What concerns me is your statement that you are making a full length resizing die out of aluminum. If you are planning to resize the cases in this die it won't last too long. If you're not resizing but only holding fired cases for neck trimming then what size will you ream the body of the die to? The trim dies that I use (Dillon) are, in fact, also FL resize dies.

      Maybe I'm missing something?


      • #4
        And trim dies are hard to resist haveing the saw blade rubbed against them.

        You might want to rethink this project.
        Ignorance is curable through education.


        • #5
          The case could be neck sized prior to trimming or after. My goal is for the trimmer die not to do anything to the neck. The purpose of the die is simply to hold the case snugly so as not to rotate while the case is being trimmed.

          I'm protyping this using aluminum, and as comparison have a Dillon RT1200 with trimming dies (it's actually a FL sizing die without the expander ball). For extended life, it will have to be made out of steel once I've worked out the prototype.

          The Dillon trimming die squeezes the neck down, which is problematic if the case was resized prior to trimming. Flat base bullets tend to not seat well, or get shaved due to the sharp edge of the case.

          To size just the neck after the trimming is problematic as the neck grows when resized. One way I've solved the when to size and when to trim is to trim just a tad shorter, anticipating lengthening of the case after it's resized again.

          So the goal is to create a die that will hold the case body snug but not size the neck, and trim the case (I'd like to use my die instead of Dillon's trimming die).

          Thanks for the suggestions!


          • #6
            I hope that you are not trying to re-invent the wheel, but it sounds to me that you're looking at this procedure the wrong way. As I was taught reloading, 1, re-size, either full length or neck only. 2. trim for length 3. taper ream inside and outside of mouth of case. This prevents shaving Copper jackets on flat based bullets. IF you propose to use cast Lead bullets, there is one more step: slightly "bell" the mouth of the case which will smooth out when the bullet is seated and the crimp is made.


            • #7
              The die will be used to trim the cases, it will be neck sized after the trim, I'd like not to overwork the neck.
              What would the problem be if you just used a good old standard case trimmer, and then neck sized?


              • #8
                This might be a subject for the gunsmithing forum.

                For trimming and neck chamfering inside and out there is nothing better than a Giraud trimmer.
                Last edited by meho; 08-18-2009, 10:39 PM.


                • #9
                  Originally posted by charliez
                  Flat base bullets tend to not seat well, or get shaved due to the sharp edge of the case.
                  Because you're skipping a step. After triming you have to debur inside and out.

                  Personally I think you're getting a little wrapped around the axle being this conserned about overworking the case necks. If it bothers you this much you need to seriously think anout case neck annealing.
                  Ignorance is curable through education.


                  • #10
                    Yes, I should really deburr inside and out, or use a case mouth expander to bell it slightly before bullet seating.


                    • #11
                      Use a Lee Collet die for neck sizing. It squeezes the neck to a stop pin (mandrel) rather than under-sizing the neck and then dragging a button back through it to bring it back to dimension. No neck lengthening.

                      David Kaiser
                      Montezuma, IA
                      David Kaiser
                      “You can have peace. Or you can have freedom. Don't ever count on having both at once.”
                      ― Robert A. Heinlein


                      • #12
                        I agree that normal trimming is so easy to do with conventional trimmers, why bother with something else? I also think the trim dies are kindof meant for when one is forming for a wildcat cartridge, and a great amount of brass needs to be removed. To just trim off 5 to 10 tho, as normal, use a trimmer.

                        Now, why not make your sizing die a bushing die, where you use different size bushings to adjust the amount of sizing to the neck portion? Nothing better.


                        • #13
                          I bought a length of 7/8-14 threaded rod some time back to use to make an occasional die that will resize nearer the head than a typical die would. It is 12L14 as I recall and that's certainly not hard or even very hardenable....but probalby a lot better than aluminum. You may even get galling between the aluminum and brass.

                          As stated, you do want to trim after sizing as it will change the case length. You also don't need to worry about over working the brass by hitting it twice. The real working comes in the first pass where you change it's size by exceeding its elastic limit. A second push into the same die does not squeeze it down further. However, if it's important to you take the neck out with a drill that is slightly over what you want. If this were a sizing die, you would have to be careful not to go too far over or you start missing part of the neck to shoulder junction....

                          Paul Carpenter
                          Mapleton, IL