crimping 38's

[Jack]

I've also found that in many pistol cartridges, cases never get to maximum allowable length, and never seem to grow. Many years ago I measured 1,000 9MM cases, and never found one that was max length. (that job was no fun at all)
Taper crimping is recommended for auto pistol cartridges that headspace on the case mount, like the 45 ACP, 9MM, 40 S& W, etc.
For revolver cartridges, roll crimping is usually recommended, but taper crimping can work well in some situations. I taper crimp 38 wadcutter loads.
270man, just to be annoying, I'll point out that case length still matters with taper crimping. A long case goes farther into the taper crimper, and gets crimped more, than a shorter case, assuming you don't adjust the die. However, the difference is small enough it isn't likely to show on the target. If you're a really good shot, and have a really accurate pistol, it might.
I would be a little wary of taper crimping a full power 357 load. But if you've tested it, and your load works, great.
What I do is roll crimp any revolver cartridge that has much felt recoil- and that might not be a magnum cartridge. A 38 or 44 Special, or 357 magnum in a light compact revolver can be a worse kicker than some of the bigger magnums in heavy revolvers.