OK, lets go back to simple geometry. a fibre bore size wad, when the powder starts burning and slams it up against the base of the ball is going to force it to take what shape? Convex against the back of the patched ball, perhaps? So what would be required to seal the bore behind the ball. pi x bore diameter divided by 2, or 1.57 x bore diameter so for a bore wad to do any good, the wad in a 50 caliber would have to be almost .8 in diameter.