KC,
I use Federal magnum primed 3-1/2" shells cut down to 2-7/8" for an 1885 Lefever thumb push C-grade damascus 10 gauge double. The same shells serve for my very much lighter DARNE sliding breech 10 gauge with 3-inch (76mm) chambers.
For geese and ducks I load buffered bismuth with shot charges from 1-1/8 to 1-3/8 oz although 1-1/4 seems to work fine across the board considering the weight of the Lefever. Powder is Hodgdon Longshot. Buffer is from Precision Reloading. Can pm you with wieght of charge if interested.
Regards, Tim
