In the book Shooting The British Double Rifle by Wright you will find lots of loading info. Most of the loads listed for the big cases like the .450#2 N.E. show 4831 powder or RL-15. The info in the book seems to point to powders like 3031 with heavy bullets as occasionally blowing doubles. Most of these bigger cases will need a filler and with out one you will probably have problems, maby even popping a barrel. If you need a filler try foam as was suggested to me by NE450#2 the stuff works great!!