I shoot it in my Marlin 45-70, Uberti Cattleman (.45 Colt) and have tried others along the line. Give 'er.
.30 Cal is unlikely to give you good results, the bore will foul quickly.
As noted above, soft cast works best but your LUBE is arguably the more important factor. Use only non-petroleum based lube. I personally favour 50/50 beeswax & olive oil. Melt it together in a double boiler & pan lube (just stand them on end). I let them cool & then use a brass tube to cut them out (I recently discovered long drawn brass tubes at the craft store, they are sized just right for .459" slugs).
Bullet Barn will indeed sell you unlubed bullets - however those are HARD cast. They won't bump up as well. But, in a modern firearm like my Marlin, they do seem to function well enough. You might get some leading, just play around with it.
A blow tube between shots may be required - just some clear fuel line, blow down the barrel. Experiment and see how many shots in your rifle you can get away with. In my .45 Colt, I've run almost 50 BP loads straight without the action getting tight or losing minute-of-steel-plate accuracy. Your results will depend on your lube, temperature, local humidity, the angle of the moon, etc etc.
Yup soap and water are your best friend with BP. Keep it real simple.
your BRASS WILL CORRODE QUICKLY unless you drop them in something to neutralize the effects (I just drop em in a container containing windshield washer fluid, at the range).
Good luck