He could tell if the calibur was one only used by one side, which would be extremely rare or if the mold was a factory mold (Federal issue) or hand made mold (Confederate) but that would be conjecture only since there are circumstances where the situation could be reversed.

The U.S. Arsenals and Armories were situation to support the States/Territories with arms when the governor of the State/Territory request issues to his troops or militias with the intent of returning those arms and equipments when done; or the state could buy the arms or equipment from the Arsenal or Armory and store them in their own armory; or an individual private citizen could buy arms and equipment for his own personal use with a certificate of belonging to a state sponsored militia or military unit. The profits would go to buy more arms. Each state got a quota of arms according to their population or need. These armories of weapons were looked upon by the state as their safeguard against insurrection or invasion. The Federal troops should have gotten their arms issues through depots supported from the National Armories at either Harper's Ferry or Springfield.

David