i was thinking the stack height was too high but that's a guess, you would need to experiment to see if it changes your crimp. i have roll crimped .410 shells ,one needs to watch rolling them too much , don't let the roller overheat the crimped area, when i did it and took them trap shooting, the crimped end shattered off. it's possible to roll the end down and melt it shut with friction.So a fairly light roll the the roll crimping device
b.p. was giving away translucent white 12 gauge shells several years ago and i had to shorten the wad to get the crimp right , about 3/16 of inch , for fold crimp