I have a Pedersoli double 12, that I love. It is Cyl x CYL bore and all hell to get 12 ga wads in. Turns out the bores are closer to 13 ga, which is no big deal as 13 ga wads are easy to get . Most times now I don't use wads, I use wasp nests instead. Works great with shot and .690 round balls.
Do you use just wasps nest material by itself?
I use wasp nest material over the powder charge and then wadded up glossy magazine paper as a filler wad. Then a thinner wad of paper over the shot. I used to use newspaper as wadding but quit after starting a grass fire.