Why not just use 4f Blackpowder ? 4f Blackpowder is ok to use full strength in the steel frame . Your not putting enough in it to blow it apart . It was used back in the day and still good to use today . Of course accuracy is very important when using it as more than a plinker . Someone I know has used his to take rabbit at 10yds .
The only problem I have seen with these is , the bore is some where around .323 and the chambers of the cylinder are around .315 . I have thought about reaming the chambers bigger but then where do I find balls to fit ? So maybe have the barrel lined ? Maybe search for a barrel of the right bore size ? Or , just leave it alone have have fun .
Oh ya! I have used a full load of T7 and lubed wad in mine with good results .
I use 4F in the .31 all the time. I usually use my own sulfurless powder or Swiss when I can get it. I ALWAYS, no matter percussion or cartridge, ALWAYS crush 2 to 4 grains of powder into superfine serpentine granulation, before spreading it out over the bottom of the chamber/cartridge case, and then load the main charge over it. Helps in ignition and distributes fire evenly to the main charge.
In the .31 I usually get velocities close to 900 fps. The little Beals shoot high at 15 feet but by 15 yards, it hits slightly under the point of aim.
My favorite exercise with this gun is "cutting strings". I would tie a string or a piece of solder to a hanging target rack and weigh down the end of the string with a washer or some old hardware pieces, doorknobs etc... I would aim for the thin dangling string and try to cut it in half with the shot. This little gun is very accurate, always hit where I lined up my sights. The very few times it did not hit, was because of my own fault, such as not properly timed breathing, shaky hands, general tiredness etc...