Here is an example of a .525 caliber round ball mold marked "Hall's Rifle". The particular example has the marking on only one side of the handles. Other examples are marked "Hall's Rifle" on both sides of the handles, some are marked "U.S." on one or both handles, and others are unmarked. These molds were very extensively surveyed and discussed in an excellent article by R.T. Huntington and Peter A. Schmidt in Man at Arms, volume 18, number 5 (October 1996) in an article entitled, "Bullet Moulds of Harpers Ferry". These molds have a sprue cutter incorporated into the handle and have a copper hinge pin (note the odd color of it here).

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