Oh dear! Lots of stuff to disagree with! For one thing, a good bit of history seems to have been forgotten.
Quote:
|
Originally Posted by Sierra
. . . On any bullet, if the crimp being applied is heavy enough to cause any visible deformation, you are over crimping! Over doing the crimping reduces accuracy. . .
|
This was part of the great argument between Sierra and Lee, who, without naming names, ranted at each other rather publicly in their advertising for a couple of years after Lee's Factory Crimp die for rifles was introduced. Sierra doesn't want their bullets indented, and Lee's Factory Crimp die does just that. Lee is correct to suggest this is the way many factories do it. Pull some Lake City M2 ball sometime; no bullet cannelure, but a hefty indentation is present around the middle of the bearing cylinder of the bullet. The LC M2 produces dubious accuracy, but so does a lot of military ball, whether indented or not. In the end, it depends on whether the more critical influence on accuracy from a particular load in your particular gun is bullet shape or if it is consistency and adequacy of start pressure? In the former case, the indentation hurts; in the latter it helps. You just have to try it to find out which applies in your case?
Regarding taper crimps, bear in mind that people have been loading ammunition for a lot longer than the taper crimp was available. The first I heard of taper crimp dies was in the 70's. I may have missed them before then, but all the 1960's NRA loading manuals have photos of the .45 ACP roll-crimped.
Here's the thing: If you are shooting jacketed bullets, except in a high recoiling revolver load you don't usually need a crimp. You often don't even need to flare the case necks to seat jacketed bullets, either. The factories don’t. A good chamfer on the case mouth will often be enough.
Lead bullets are another matter. For one thing, they are lubricated. If you don't crimp a lubricated cast or swaged lead bullet, it is often possible to push the seated bullet deeper into a case with your thumb. This is particularly unsafe in a small capacity case because it will see a dramatic pressure rise if a bullet is seated even modestly deeper than the load was developed for. As a result, a crimp is needed to keep the bullet in an autoloader cartridge from being pushed in when recoil bumps the front edge of the magazine back against it. A light roll crimp or a firm taper crimp will engrave a lead bullet with a ridge that prevents this.
What about headspacing on the case rim? Well, truth to be told, most straight, as-issued 1911's and a lot of other self-loading pistols have enough slop that the chamber is actually too long to headspace most ammunition on the case mouth. Instead, the cartridge's forward location is regulated by the extractor hook. In the case of the .45 ACP, this doesn't seem to impact accuracy too badly when shooting jacketed bullets. They are tough enough so the case backs up against the breech face as the bullet works it way onto the rifling and more or less lines itself up. Lead bullets, on the other hand, engrave so easily that if they start out canted to one side by pivoting on the extractor hook, they enter the bore slightly canted, and that plays havoc with their accuracy.
So, what did all the old-time, pre-taper crimp softball shooters do? They headspaced on the bullet. You simply seat the bullet out a little further. Just enough that when you drop a loose round in the barrel, the face of the case head is flush with the breech face. In some extreme cases, where the barrel extension (hood) was welded for fitting but remained too long on a 1911, this headspacing setup made round nose bullets stick out too far to fit in the magazine. But with more blunt-shaped target and semi-wadcutter and truncated cone bullets, it usually isn't an issue. And, it can cut lead bullet group sizes in half, as it did for my original Goldcup.
For the 1911 in .45 ACP, barrel gauging headspace looks like the illustration below.
I also use taper crimp dies for lead target loads in revolvers. Why? The light loads don’t need a heavy roll crimp to prevent bullet back-out, and the taper crimp works the case mouth brass a lot less. The result is the cases last through many more reloads; as many as 50, while roll-crimped case mouths start splitting long before then.
Hope this helps,
Nick