.36 Iron mould with sprue cutter, for commercial Colt Model 1851 & 1861 Navy percussion revolvers. Straight leg mould, stamped “COLT’S PATENT” with an apostrophe, on the top face of the sprue-cutter, close to the hinge. The two cavities are for a round ball nearest the hinge pin and a heeled conical grease groove below it. The groove helps facilitate loading into the cylinder chamber. The locating pin is on the right leg. The finish is blue.