I'm having a great time shooting this shotgun. Trying out ways and means. Paper cartridges work just fine. Have used paper and linnen/flaxen fibres to separate pellets from powder. But, found something else! After I felled some really old trees, there were these flaxen-fibres-looking thingies hanging from the stem and branches. After searching on the internet it seems to be a mushroom species called lichen, long entangled yellow-grey stuff. like a beard. It doesn't smolder when pressed, but is quite spongy. Proved a super material for packing cartridges. The native Americans used it for treating wounds, as it has some sterile function (which might be a negative factor in a live load).
Will try to get up some pics, just get to cool down first.