I have not tried anything heavier then the factory 180s, and my handload is a 165 Hornady SST. But, since the original 30-40 chamber dimensions allowed for the 220 gr round nose, and and the original 30-30 barrels were the same 1 in 10 twist, they should work great with the 220s. Later this summer I hope to get to try some heavy cast in this one. I looked for some time for one of the earier SB2s, with the cut riflings just to use with cast.
I can highly recommend the shop that did this one. Capital Sports, Helena, MT, 406/443-2978. They charged $100.00.
They also have 303 British reamers, so I'm watching for a used 7.62x39. On that one I will need to change the extractor for the rimmed case.
Wally