Good point, Martin - I've never used a roll crimp, as I've noted - somewhere.

I've always used a folded or partically folded crimp.

The early 'punkin balls' shotshell loads of the 1920's through 1950's, used a .640" or .650" ball. They were VERY small, and I'm pretty sure, a rolled crimp was used. Even if the bal rode over the crimp, the wads would push it out, I suspect. I also suspect no damage would occur. The groosly undersided balls, coupled with them sitting on a hard card wad which allowed them to bounce down the bore, contributed to their misserable accuracy.