I agree with Sarge. The taper crimp may only remove the flare when seating jacketed bullets, but with lead you want it to bite into the bullet a little. If you don't, you'll find lubricated lead bullets, especially with brass that's been reloaded a number of times, can be pushed into the case with your thumb. That means you are in danger of the bullet seating deeper when if feeds, and that can create pressure problems. The bite into the lead creates a stop so that doesn't happen.
If you are crimping in like that, you don't want to depend on the case mouth for headspace. It will still work if you don't get it below the SAAMI diameter minimum at the mouth (0.4670") of the loaded round, but I find I get better accuracy and less leading if I let the cartridge headspace on the bullet in the throat. Some designs don't feed well that way, but the usual target wadcutters seem to do fine with it (third from left, below).
