Given the popularity of sub gauge inserts there is a lot of leeway with plastic wad expantion.

The old reloading manuals of the 1960's always stress proper shell lengh for the chamber, now we shoot 2 3/4" shell out of 3 1/2" chamber without a second thought. Chromed barrels shed lead with a simple cleaning brush.

Nitro card and cushion wads is works fine in my BP loads but it is the pattern board that tells the tale.