The 2 1/4" would be close to the high vel. .38/55 loading of 255gr. (Velocity wise)At 1,825 to 1,850fps, iirc.
Seems to.me, the .38/55 original load and subsequent smokeless loads duplicating the BP load, was a 255gr. at about 1,320fps.
The target shooters of the day, used 300 to 320gr. cast bullets in their target rifles.