Somewhat back on track, thanks to loaders like Joe Swanson who pioneered motion picture blanks, we now have a product that produces CONSISTANT results. Not to diminish anyone else's efforts, there are other blank manufacturers that have copied and improved the designs with new powders, refined crimps and profiles.
It wasn't until we had reliable ammunition that improvements in gun blanking, especially pistols, could more quickly evolve. I'm sure that Steve C would concur that "our guns are only as good as the blanks"
Regarding the crimp, it also keeps the powder retained and burning longer than wads thereby resulting in consistant pressures especially critical for semi/full auto gas operated guns. Without that the 1/4 and solid plug loads (9mm solid plug only 1-2 grains of powder!!) would be even more tempermental.

4570guy