I've seen them, but never loaded them. I know the conical bullet has a hollow base with a very large cavity, so I'm guessing, even at gallery pressures, the soft, pure lead bullet's skirt expands to grip the rifling. I seem to remember an old article in Handloader Magazine called "All About 44s" by Ed Yard that had load data for this...? Was just a few grains of Bullseye, IIRC. A very light load of any fast-burning, easy-to-ignite powder should work. Velocities were in the 550-675fps range, again, if memory serves... Interesting yet odd question. What are you loading these for and what are you shooting them out of?