For muskets and trade guns of 20 gauge and larger the maximum powder load where I reenact is 120 grains, but I only use 100 grains of 3Fg. It burns faster so produces a nice pop. Were I to shoot live ball or shot I'd be using 2Fg.
For rifles, and for guns under 20 gauge, the rule is powder load should not exceed 1.5 x the caliber. That would give me 80 grains in my .54 of 3Fg. I use 70 as that is what my charger for the rifle provides. Plenty of pop.
We are not allowed to ram down anything on the powder, not to use the rammers when on the field. Cartridges must be in either a leather or tin container with a cover. Guys doing Native with a wool shooting bag use a leather insert with a leather flap concealed in the wool bag. Cartridges only, no loading from a horn, and horns with powder may not go onto the field either.
LD