from the old forum:
I have read around and noticed that if we crimp too much on a cast bullet it destroys diameter as cast. Is this correct? If so is it possible to crimp heavy pressure loads i.e. 454, 475, 500 and still have a proper cast bullet as we cast it?
Reply: Yes and no.
The Lee factory crimp die for pistols tends to squash the portion of the bullet that is inside the case. The Lee die has a resizing ring at the entrance to the die. The resizing ring was intended to iron out any buckles in the case. The problem is that as the ring resizes the case, it also sizes the bullet that is inside the case. In theory, that's bad news for cast bullets, though some Lee loads shoot OK despite the bullet damage -- probably thanks to obturation.
This is not to be confused with the Lee factory crimp die for rifle cartridges that uses a collet rather than a resizing ring. The collet system is a great idea. IMHO, Lee should use the collet system for pistols, too, rather than the stupid resizing ring.
BAbore has reported that the Hornady pistol dies also squash the bullet. I have no experience with the Hornady dies, so I'll have to take BAbore's word for it. I would be suspicious of any die that has a resizing ring or that applies a taper crimp, in addition to the roll crimp.
Here is what I do for wheelgun loads where a good crimp is needed.
1) use a deep seated bullet design. The deep seated design gives the case more bullet to hold onto. Sometimes there are legitimate reasons not to use a deep seated design, like my 357 rifle bullet where I am trying to maximize powder space, but usually a deep seated design gets the nod in short barreled wheelguns.
2) turn the pilot on the case flaring die down to 0.005" - 0.010" smaller than the bullet. These pilots are almost always too big as they come from the factory. Basically, you only want the pilot to be big enough to iron dents out of the case, and to guide the flare straight into the case. You don't want the pilot to actually increase the case ID.
3) then put a modest roll crimp with a plain jane crimp die. I happen to use Redding dies (not their profile crimp, though).
4) use an inertia puller to test the bullet pull and to see if the bullet was damaged by the case tension. In some, but not all cases, a soft cast bullet will be squashed if the neck tension is excessive. So far this has only happened to me in the 30-06, but not in handgun cartridges. The only way to know for sure is to pull a bullet. Inertia pullers are cheap.
My standard roll crimp held the bullet much tighter than the Lee FCD, as measured by counting the number of whacks required to dislodge the bullet with an inertia puller on a 44 magnum cartridge.