I've shot cast bullets at targets in the .375H&H, Ruger #1 rifle.
I used a light load of 4198 under a Lyman bullet #375449, which casts at about 265 gr.
The velocity is probably about the same as a 38-55.
This load will put 10 shots in to one big hole at 50 yds and is fun to shoot.
I use a 3/4" sized piece of dacron fiber to keep the powder near the primer.