Here is another bullet that looks promising for the 56-50 Spencer when using black powder. It is the
Lyman 515139, currently available through Buffalo Arms Co. I bought one to try it in my 50-95 Win. The bullet has 3 grease grooves and a beveled base. There is no crimp groove, but it would be a simple thing to crimp just forward of the front driving band. When cast of 20:1 @ 750F, the bullets weigh 343gr with driving bands of 0.518" diameter. I probably won't get a chance to test it in my Spencer carbine until this time next year; all my brass is loaded for the upcoming season (load all winter, shoot all summer, shoot year round when you can). If someone has experience with this bullet with black powder in the Spencer, I'd like to know how it worked out. One more thing, Lyman recommends the 191 top punch - I had to modify mine w/epoxy to keep it from gouging the bullet noses something fierce. Good shooting to you.
Well, its Feb, 2011 7 I finally got around to trying the Lyman bullet in my Spencer. Bottom line: The Rapine bullet works much better in the Spencer, more accurate & feeds better.
Sorry it took so long to do this. But, hey, I am still faster than most drifting continental plates.