I used an LBT slug to make my pound cast. It was about 0.020" less than the bore size. I went through the procedure and the slug came out easily, but no rifling marks appear. I need to have it long enough that rifling shows, correct?
I made some slugs much closer to bore size by casting them in drilled holes in a block of wood (sassafras) . They didn't come out smooth. I've been thinking about making some more using plaster of paris and using the drill shank to make the slug holes. I'm a little concerned about any residual moisture contacting molten lead. If not plaster of paris, is there some other way to make a disposable mold? Maybe use denser wood instead?