roll crimp -vs- taper crimp

[Edubya]

In my search for more learning, I started trying to understand the need or the desire of the roll crimp -vs- taper crimp. Found a couple of, seemingly good explanations (at least 'good' in my simple, under -educated mind). I need the opinion of a higher learned reloader. What's your opinion?

Q. The rifle bullet I'm loading has a crimp groove, but the cartridge length recommended puts the groove out of the case. Should I change the seating length to make the crimp groove line up.

A. No. Not all rifle cartridges require crimping. The groove on the bullet is positioned for those that need the crimp. If the recommended seating length puts the crimp groove above or below the case mouth, we determined that crimping was not needed. Having the crimp groove above or below the case mouth has no adverse effects on accuracy or performance. Speer bullets - Reloading




QUESTION: Dear Rabbi Mermelstein:

In one of your responses you advised the person to taper crimp .38 Special cases using the Lee Factory Crimp die, rather than the traditional roll crimp. Why? My understanding is that roll crimping revolver cartridges is SOP to the point of being dogma. For example, I use a Lee Factory Crimp die to roll crimp my .44-40 Winchester hard cast bullet reloads (at least I THINK it is a roll crimp).

Bill

ANSWER: Dear Bill,

In the infancy of modern reloading, perhaps 60 or 70 years ago, the roll crimp was all that was available. The C-H Tool and Die Co. invented the taper crimp die almost two decades ago. Continue to roll crimp if you want. However, you will have to check that all you case lengths are identical within, perhaps, .002 inch. If not, the roll crimp die will give non uniform degrees of crimp. If the case is a few thousandths longer, the case mouth will buckle and the round will not chamber. I haven't used anything other than a taper crimp die for 15 years for all my handgun loads; even for magnum loads using a slow propellant that require a very heavy crimp. The taper crimp die is far less fussy about small deviations in case lengths. Better to spend your time shooting than trimming cases. Your Lee Factory Crimp die is a different concept from both the taper and roll crimp. It, too, will overlook deviations in case lengths. I use Lee's Factory Crimp die on centerfire rounds that I handload for all my lever action rifles.

GunOwnersAlliance.com - Ask the Rabbi: Roll Crimp vs. Taper Crimp

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