Using my very failing memory, these molds from Dixie Gun Works were originally designed from Civil War carbine bullets. There were lots of different molds. This one below is a .515" bullet. I'm kinda sorta sure the one groove wasn't for lube but for the string to attach the paper cartridge. The bullets were dipped in tallow to lubricate. This one was new-unused when I bought it. Pretty sure I didn't pay much for it, maybe $20 off ebay. It drops good bullets....if I can figure out how to remove the sprue!! I might try a couple in the Swedish 12,7x44R rolling block... just to say I did.