Jim,
When working with a new hull or load, I load one hull with everything but the crimp, then leave about 3/16 to 1/4in. above the overshot card and crimp.If everything looks good I trim all to that length. If not I adjust a little more or less on the next one till I get the crimp I want. Not all plastic and paper roll the same, so some experimenting may be required.
The roll crimp tool will stop when it hits the overshot card,have never had to set the stop on the press. Roll crimps are easy to make and look cool just like the old guns we shoot them in. :>) Here's some info on Ballistics site. HTH Bob
ROLLCRIMP