Thanks, Gil.
There is also more capacity due to the inside of the case being larger diameter because the brass wall thickness is so much less than plastic. I tried a Rem .410 plastic shotcup in the case and it will drop to the bottom without any contact on the inside "walls". If I were to try using them I would have to use a card wad over powder to prevent migration around the shotcup. I assume the base of the plastic shotcup would expand to seal the gases behind it, as it does when fired in Chambermates and a larger bore gun, but it would take patterning and playing around with that to tweak the load, I would expect.
Good, clear instructions from RMC, thanks for the link.
