
I want to develop a load for this rifle that has the same ballistics as the original BP load, which means 405 grain cast bullet leaving the barrel at around 1,300 fps or slightly less. I've been trying a few different powders and it looks like SR4759 and 2400 will be my two powders of choice. Both of them have similar pressure curves to BP for the same bullet and ballistics. Today I tried 2400 for the first time, putting 21 grains behind a plain base cast bullet of 405 grains. It gave 1,254 fps with an extreme spread of 77 fps. I'd like to boost this up another 40 fps but here's the results, 5 shots into 2 & 5/16" at 100 yards. I was shooting with open iron sights, so I'm sure the limiting factor is me, not the rifle. Here's a photo of the target ....

My SR 4759 load put 4 shots into 1 & 1/4" at 100 yards, but the fifth was a flyer that went in about 2" low, so I don't know about that load. I've got some more loaded up and will try it again, just in case the flyer was me. This rifle is going Whitetail Deer hunting this fall, along with my original Winchester Model 1873 38-40.