Registered users: shooter, bigdog02, Bill M. Posted: Wed Mar 29, am. All firearms made in Italy are required by law to be tested by the Government Proof House, which marks the firearm with several symbols, one of which is a code identifying the year in which the firearm was proofed. A key to the code is shown below. Note: The date code is not a part of the serial number. Read the paragraph below to learn where to find the date code.