I've had a couple of rifles and a Colt Army Special in .32-20. Great cast bullet cartridge, in fact no advantage to using jacketed bullets unless you just want to use them. Bore sizes can vary considerably.

I haven't been without at least one .32-20 firearm in the last thirty-five years or so, but haven't really figured out the usefulness of the cartridge, sort of like the 7.62x39.

Get a regular Lyman manual or the Lyman cast bullet manual, lots of safe load data. I'd stay away from the older hot data that's still out there, particularly if you have older Colt and S&W handguns.