RE: Marlin 45/70 ?
I have the 1895 rifle as well. Factory loads (that mimic the old bp loads) are about like shooting a .410. I have hand loaded mine with a 405gr hard cast bullet up to about 2100fps, and that gets pretty brutal. You wouldn't need anything approacing that for deer. I have settled on the same bullet, at about 1700fps for a standard load, and it isn't bad to shoot at all.