You are supposed to only remove the flare when you taper crimp a pistol cartridge in order to not damage the bullet. Why then, are you supposed to "firmly"crimp a revolver cartridge? Would you not as well, damage or shave the bullet? Lead in particular?

Most pistol cartridges headspace off the case mouth. Most revolver cartridges (except the 45 acp using half moon clips) have rims so you can bend in the case mouth as much as you want as long as you don't distort the case and prevent it from slipping into the chamber of the cylinder.
Crimp style has little, if nothing to do about concerns for damaging the bullet.

'Pistol' (semiauto) bullets don't always have a crimping groove to roll crimp the brass into. Placing a roll crimp into them will indent the circumference of the bullet with the brass case.
Plus many semi auto handgun cases headspace on the case mouth itself. They need a clean, sharp edge there to maintain that headspace. A rollcrimp on the mouth of the case takes that edge away.
Just push the bell/flare back into position and you're done if the dies are right.

Revolver bullets have a crimping groove in their design generally. Someplace for the turned over brass casemouth to go w/o damaging the bullet itself.
Plus revolver rounds are usually a rimmed case and headspace on that rim so the sharp defined case edge at the mouth is not needed to headspace the round in the chamber.
You don't have to roll crimp if you don't want too, but can w/o headspace problems or bullet damage.

I found the taper crimp needs to be done "just right". Not enough, and FTF. Too much, and maybe headspace/bullet distortion issues. Just wanted to ask about the roll crimp. Thanks

Also important to remember is that if bullets back out under recoil on a wheel gun, they can jam the rotation. This, however, is not a problem for semi-autos. Thus, roll crimp for revolvers because you can (at least if you need to), but not on autos because you both can't and don't need to.

1. The reason for taper crimping is because of case design and not because of the gun it's to be fired in or the bullet used. Straight walled cases with no belt or rim headspace off the mouth of the case.

2. With a Lee Factory Crimp Die you can, and I do, crimp bullets without a cannelure to be fired in a revolver. There is no reason why a groove made from crimping should impair bullet performance more than would a factory applied cannelure.

3. Regarding taper crimps, if you flare just enough so the bullet can be seated in the case and no more, you can forego the taper crimping.

Taper crimps are a solution to a non existent problem; they were invented by the die companies to sell more dies. Or to make up for mis-managed FL dies, expanders and bullet diameters. Just make the bell straight, and if your dies and components are in sync, you will never have bullets move. This is from loading thousands of auto ammo since 1966 without owning a taper crimp die. For revolvers, as stated, you might need a roll crimp.

Auto pistol rounds which headspace on the case mouth are indeed better served by a taper crimp. To adjust the taper crimp right, add twice the case wall diameter to that of the bullet and you're done, no more no less.

Since I started using a Dillon XL650 press, whose dies are ambivalent and can be adjusted to either roll or taper crimp, I've been taper crimping my revolver ammo too. The bullets stay put even in .44 Mag full loads but the main advantage is that, contrary to the roll crimp, a taper crimp is not sensitive to case length. This is quite an asset when you consider the hassle of trimming cases (which need to be FL sized first) prior to load in a progressive press.

quote:

Originally posted by dpcd:
Taper crimps are a solution to a non existent problem; they were invented by the die companies to sell more dies. Or to make up for mis-managed FL dies, expanders and bullet diameters. Just make the bell straight, and if your dies and components are in sync, you will never have bullets move. This is from loading thousands of auto ammo since 1966 without owning a taper crimp die. For revolvers, as stated, you might need a roll crimp.

+1

I, too, have loaded thousands of rounds for semi-autos (.380, 9mm Luger and .45 ACP), and all I do is to "Just make the bell straight."