Two of us bought Pedersoli 12 ga. sbs shotguns when they first came on the market. We quickly found out that modern card and fiber wad columns caused blown patterns in our new m/l shot guns. Experimentation eventually showed that the culprit was the wad column. We subtracted the felt wad component and used a.125 card on top of the powder w/ a 1/2 of a .125 card wad on top of the shot.
Only thing I could understand from our experiments , is that the thinner , lighter card wads slowed down and dropped out of the shot cloud more efficiently than a standard felt wad component. Seemed like , the more wads we mixed w/ the load column , the worse the shot pattern got. Back then there was lots of game in Pa.. , so we tested our loadings on squirrels , pheasants , rabbits , etc. w/ excellent results. oldwood