 There are only two overloaded firings to avoid excessive stress to the arm, especially the barrel which is the main part suffering this overload beside the chamber (when not part of the barrel) and the locking mechanism.After the test, the arm is disassembled by the proof house technicians for nondestructive testing looking for magnetic flux leakage through fluoroscopic lamp in a dark room.Many manufacturers package the casings from a firearm's proof ammunition in a sealed envelope accompanying the firearm so that authorities in C.I.P.-signatory states and civilian purchasers in other countries can conduct an independent examination if they desire.