I've never used a roll crimp - but see no reason why it's use should not be used. It would allow heavier charges of black powder, or more wads to be used. I've been meaning to buy the Lyman roll crimper for about 30 years but never got around to ordering one. Wad column heights would have to be absoltuely perfect for a good roll crimp I think. With a folded crimp (in my press) if the wad height is a bit high, no problem - the ball merely shows through in the centre of the crimp. Because I live fairly close to a trap range and also use 12 bore cases, both spent trap wads (for cutting the gas checks off the bottoms) as well as hulls are free for the taking. When using black powder loads, I discard the hulls after one shot. In high humidity areas, they take on moisture from the fouling within and I refuse to clean plastic hulls.