A friend gave me an old mold the other day. It is single cavity marked 452374 with attached handles. No other marks. I assume this to be Lyman as that is their number for the 45 Auto RN bullet. What is strange is that the blocks are Brass! Never seen anything like this. Any idea how old this is? Also, the original sprue plate is missing. I would like to make one to restore this old mold. What material should the sprue plate be made of and how thick should it be? Any advice would be helpful. Thanks, Jeff