Reloading dies - Taper or Roll crimp?

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  • Atrox88

    Gold Member
    Jan 7, 2016
    1,245
    Carroll County
    I want to order some dies and they give me a choice of Taper or Roll crimp.
    They are going to be for .38 Spcl & .357 Magnum. What's the difference?
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    Roll crimp for cases having rims wider than the case diameter(case seats on its rim).38 sp, .357 mag etc. Taper crimps are for cases with rims the same size as case diameter(the case actually seats in the chamber on its case mouth) like 9mm, 10mm, .40 s&w etc
     

    85MikeTPI

    Ultimate Member
    Jul 19, 2014
    2,699
    Ceciltucky
    I believe the roll crimp into a cannelure will give the strongest grip on a revolver magnum pistol round, to keep the bullet from moving in/out during heavy recoil.
    The taper crimp will be more gradual and can be used without a cannelure on FMJ. I don't load for revolvers, so I always get a Lee Factory Crimp Die for Semi-auto loads.
     

    Uncle Duke

    Ultimate Member
    MDS Supporter
    Feb 2, 2013
    11,667
    Not Far Enough from the City
    Op, much of your answer depends upon most of your bullet choices and applications, most of the time.

    In general, if you're going to buy just the one die set, buy the set with the roll crimp die for the cartridges mentioned. Where it perhaps isn't perfect for an application necessarily, it can be used to be good enough.

    Roll crimping is the choice for use with jacketed bullets with a cannelure, and for cast bullets with a crimping groove.

    Roll crimping shines with heavy loads, where you want load consistency and don't want revolver recoil moving bullets in the cylinder forward, as they can then hang up cylinder rotation. Also important for applications involving mechanical leverage for chambering, leverage that can otherwise have the potential to cause bullet setback, (such as but not limited to) lever action rifles popular in these chamberings. Think "I'm not loading these rounds into a chamber by hand", like I am when I am loading a revolver cylinder. So given that these bullets are going to banged around a bit in chambering, I still need them to stay put.

    For light loads, and for plated and swaged bullets without crimp grooves or cannelures, taper crimp dies can shine. These bullets are typical in the realm of the autoloaders, but are certainly not exclusive to them.
     

    Biggfoot44

    Ultimate Member
    Aug 2, 2009
    32,881
    The cliche default answer is you want Roll crimp . And 99% of the time a good answer .
     

    Rockzilla

    Ultimate Member
    Feb 6, 2010
    4,516
    55.751244 / 37.618423
    I want to order some dies and they give me a choice of Taper or Roll crimp.
    They are going to be for .38 Spcl & .357 Magnum. What's the difference?

    For what you a going to do Roll Crimp
    Roll crimp "rolls" the case mouth into the cannelure (crimp groove if present) of the bullet therefore holding the bullet in place.

    Taper Crimp basically takes the case and gradually tapers part of the case & mouth in and is not even noticable like the roll crimp.

    Cases that "headspace" on the case mouth you Taper Crimp
    now not to confuse you and preference not to your question
    I taper crimp 5.56 / 7.62 when needed

    -Rock
     

    Harrys

    Short Round
    Jul 12, 2014
    3,362
    SOMD
    I have used a roll crimp for all my loads, they hold the best especially for large caliber rounds.
     

    Biggfoot44

    Ultimate Member
    Aug 2, 2009
    32,881
    The small exception was that back in the Golden Age of Revolver Bullseye , some people used taper crimp for flush seated swaged wadcutters . And once upon a time , it was a slight blip of people experementing with .355 dia lightweight jhp ( in weights associated with .380 ) to try to get really high velocities from 2in
    38spl , and they would try taper crimps . ( Wasn't a great idea, and didn't catch on , but circa 1980 it was a micro thing to try .)

    Some people * In Theory * think that taper crimp does less deformation to plated bullets with thin plating . Is there anything to that ? I personally can give an absolute no, but in my experience , a light roll crimp with plated can give sub 1in @ 25yds , so I never felt a need to try taper .

    Other than obscure or experemental stuff like that , go with roll crimp .
     

    Atrox88

    Gold Member
    Jan 7, 2016
    1,245
    Carroll County
    Thank you all. Most helpful information. I used to dabble with reloading rifle cartridges (223, 308, 22-250) ages ago but I didn't recall a taper vs roll crimp with those rifle cartridges.
     

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