have owned a few .30-40s, including two Krags, a reproduction Winchester 1885 single-shot, and an over-under double rifle built on a 20-gauge Ruger Red Label frame (the original RL, not the present model).
In all of them a 180 with 48.0 grains of IMR or H4350 has shot very well, usually getting around 2400 fps. Would guess it should work with a 170.
