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Did I buy the wrong set of dies

Discussion in 'The Ammo & Reloading Forum' started by Big Chevy, Sep 4, 2012.

  1. Big Chevy

    Big Chevy Member

    Joined:
    Mar 10, 2012
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    Why does RCBS carbide dies for .38spl & .357 mag come in both taper and roll crimp? I bought the part number 18215 group B, but I think I need part number 18212 group B. I just figured it would be a roll crimp because that's what you use for the .38 and .357. Just want to know if I bought the wrong one. if I did I think I will put it up for a giveaway.
  2. Texxut

    Texxut Member

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    I'm not sure why they would offer a taper crimp die for 35/357. A roll crimp is what you really want for those cartridges. If it hasn't shipped yet, call and change your order. If it already shipped, Call RCBS and see if they will swap you for the roll crimp die.
  3. myfriendis410

    myfriendis410 Member

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    I disagree. I use a taper crimp die out of preference for all of my pistol stuff. It really cuts down on brass trimming, and increases case life dramatically. You've got a lot more flexibility as to where you seat your bullet too. I would strongly suggest you keep the taper crimp die set.
  4. 243winxb

    243winxb New Member

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    18215 is a taper crimp. Try using it, then run a test. Load a cylinder full, fire all but the last round in the cylinder. Check the COL, has the bullet moved more than a few .001" If very little movement, your OK. Neck tension mostly keeps the bullets from moving, but a roll crimp does help under heavy recoil.
  5. JLA

    JLA Well-Known Member

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    Also in the 70s the AMU developed a competiton cartridge called the .38AMU. it was essentially a .38 spec with the rim turned to match that of the .38 super. Designed for reliable feeding in a 1911. As far as i understand you load them with .38 special dies (data is same as .38 spec too) and a 9mm or .38 super shellholder. but since its an autoloader cartridge the other part of the development was that it needed a taper crimp so it could headspace, since they got rid of the rim.. Hence the invention of the taper crimp die for .38 spec.

    Plus, as 410 says above. some folks prefer a taper crimp for thier .38 specs. it lends well to brass life and since pressures are low, its sufficient in that cartridge.
    Last edited: Sep 4, 2012
  6. Texxut

    Texxut Member

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    Well, now I know what the taper Crimp is for in .38 special, Thanks JLA.
  7. Twicepop

    Twicepop Well-Known Member

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    The taper crimp die would be useful for plated bullets and other non-cannelured bullets such as soft lead swaged bullets and the like. A separate roll crimp die can had through RCBS for bullets that require a taper crimp. A seperate die will ad to the versatility of you die set. And as an added note, I've found that I get a better crimp when done as an additional step after bullet seating.

    those who beat their guns into plowshares, will plow for those who didn't
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