Jim;
In so far as I know all wads are currently marked for the gauge shells they are intended to be used in. n the ones which I have actually measured the run around .020" larger than nominal gauge size.
I don't believe this would have any affect on using modern components. Only pointed it out in case someone tried to relate it to some very old loading instructions from the past.
Loading instructions in a 1913 LAC catalog for instance call for loading wads two sizes larger with black powder. I can really only assume this was meant for use in brass cases. Using present components it would be extremely difficult to insert a 10 gauge wad into even a thin wall 12ga brass shell. We would instead use one of 1 size larger or an 11 gauge wad.
Likewise these instruction call for 1 gauge oversize when loading smokeless powder. Again I "Assume" this to be with paper cases. If one tried to load a modern 11 gauge wad into a paper case the likely result would be a severely mangled case, it would simply be too big.
