This tool is the large frame variant of what has been called the "second model" Browning tool and is for the 40-60 cartridge. Art Gogan and Fred Selman presented an excellent review and analysis of these tools in an article entitled, "The Browning Bros. Loading Tools", published in Man at Arms, volume 15, number 6 (November-December 1993) p. 24-31. The second model tools are unmarked except for caliber and came in at least three sizes to accommodate various lengths of cartridges. Browning Bros tools are rarely encountered in any model.