I've noticed that the Cheddite hulls are a little larger in internal diameter and find that the Gualandi wads, which are a little larger in diameter work well. I use the 1618 in 2 1/2" hulls with 17gr of PB and 7/8 oz shot.

P.S. With the clear and red Cheddite hulls you can see if powder is being pushed/blown from under the wad and up the sides of the hull.

Phil