Sam,
I would like to put a little input in this.
For some reason mow days shooters using black powder seem to feel that they need deep grooves to hold a lot of lube. Well all those deep grooves just blow lube away unused.
If you look at the old original grooved bullets they had a lot of grooves and and the bands were narrow and pay particular attention to the ogives that end at the front crimp groove or first driving band. Those ogives were designed to minimize dry lead to come into contact with the bore that the hot friction would contaminate the bore especially if there is a lot of tin in the alloy mix. Lead and tin makes it a solder and solder will stick to metal when heat is applied. Soft bullets mostly lead you will not get the lead smears in the bore. If you ever have shot the smoothy rifles where you push a mini ball or even shot guns the lead smears are just not a problem. Try soldering with just pure lead.

Bullets like the 121 in the center and the .44 Maynard round on the right is an example of what I mean about the ogives used back then.
The knurled bullets I use if I want to let people use when I let them shoot my rifles at the range need no fouling control. Those diamonds are shallow just below the depth of the rifling and that is enough to keep the fouling under control for many shots.
John's wide groove bullet is a good bullet for the lever rifles but in reality it does not be that deep.