I have a 94, heavy bullets are not suited to it, but they seem to be the norm for the Single Shot rifles like yours.
I shoot a 265 from R and R, a magma design, works well. I also shoot a 285 gr version of 375296, also works well.
My 94 is off the map spec wise, 379 is the largest bullet that will chamber, and my bore is bigger than that. However, it shoots both of these well, and one is soft, 8 BHN, and the other hard, 18 BHN. Both are gas checked. I use H4198 or IMR3031, are you going smokeless or BP. I've tried my loads in a second 94, they shoot in it as well, and I think the bore is even bigger in that one.
If you buy a mold, I'd suggest a Lyman 378674, looks OK, but I don't have any experience with it. Most casters wouldn't mind casting you up some, if you supply the mold, and the lead, and a pop or 2. also see Accurate molds, they have a large selection of mold designs.
