That Lee bullet was made for trapdoor rifles. It has a hollow base because bore dimensions varied so much in those original rifles and carbines. I shoot mine in a rifle, unsized, lubed with my home brew lube. Your bore is probably more standardized, but you could slug it to get exact dimensions. You have to order the mold direct from Lee, I don't think Midway or anyone else carries it as a stock item. You can also get a brass powder compression die from Lee. Compressing that powder charge in 45-70's scares the crap out me. Takes a lot of muscle on the lever. Lee also says to always use a wooden dowel or mallet to hit the sprue cutter, believe them! I'm on my second one.