RE: How much black powder in a 30/30 load?
You do not need alot of tin. Just drop them in cold water directly out of the mold(while hot). This will add three or points of hardness(on the Brinell scale). That should be plenty hard enough for up to 2200 fps.
If you are going to use BP(Great Idea). Start out with 25 grains of 2F, and use a drop tube. Tom.