The slide will usually read Cal. 9mm Makarov or simply PA 63 . Note: 9x18mm Makarov is not the same as 9x19mm Luger/Parabellum or .380 ACP.
Find the serial number stamped directly into the left side of the aluminum-titanium alloy frame. Ensure you are not looking at a laser-etched US importer serial number. feg pa 63 serial number lookup
(ensure it is unloaded). Check the barrel hood and underside of the slide for hidden numbers. The slide will usually read Cal