Not long ago I was digging around on something else and found a reference to using cast bullets in .30 C, which I've done, but this was specific to use in the Ruger Blackhawk chambered in that cartridge.
Then someone mentioned using .32-20 cases trimmed appropriately in this pistol. Some apparently can use them unmodified, others the rim has to be thinned. This cartridge headspaces on the case mouth, so you have to be careful to have uniform case lengths, and either not crimp or a slight taper crimp, and they do still have a tendency, in some guns, to be sticky on ejecting; a rimmed cartridge should prevent that.
I know a guy with one of those. And I have some .32-20 cases left.
Once more demonstrating my problem with messing with things to see how it works, borrowed the use of the Blackhawk. The cases, after being run through a .30 C sizing die would chamber, but the rim was too thick for them to rotate through, so some time at the lathe thinning them, after which they would work.
The research had shown that using .32-20 loads with these cases was well within the pressure levels, so I took some 100-grain semi-wadcutters cast for .32 S&W(and .310 Cadet as it worked out), sized them to .310, lubed them, and loaded them just over the minimum listed for .32-20. Then loaded some .30 C cases with the same load. Standard .30 C on the left, case loaded with the SWC center, .32-20 case on the right.
According to the numbers these should be between 750-800fps, so far less flash and boom than standard loads in this(believe me, it's impressive) for general plinking. We'll see how it goes.