This might be a good time to add some nonemclature comments. A "proof" is a mark indicating successful passing of a proof firing test. An acceptance mark indicates acceptance of a finished arm into customer's ownership. Naval property marks may also be acceptance marks, although I don't know, but certainly indicate ownership of the arm by the navy. Finally, inspection marks are indications of successful passing of parts of the manufacture/assembly process for the arm usually including final assembly and meeting of all engineering specifications. The crown/letter right side receiver marks are inspection marks. Eagles are usually proof marks or final acceptance inspection marks. Crown or Eagle/N is a final acceptance mark. Eagle or anchor/M is a property, and possibly an acceptance, mark. Unit marks are a field marking used for identification and inventorying purposes.
Do these seem correct?