Marrakai, all plastic hulls are not created equally I've found.
Some have very soft plastic, while others are quite hard.
I did not get many loads from each hull, due to the abrasion/melting that happens with the black powder - 3 at most, but generally 2.
Due to having an unlimited supply of hulls from the local trap range I no longer clean them. Seems most everyone today, shoots factory loads.
1 shot with BP and I now discard them.
I agree with Mike on the rate of twist, if faster than his guess, likely not faster than a 60" rot.