it happens, and when caught months later (poor record keeping, or intentional misleading records, or just lazy people not checking serial numbers) there is always an investigation and usually people lose rank or freedom.
one m16 recently wasn't noticed (never reported missing) until it was found in a traffic stop turned drug/gun bust. the unit it belonged to tried to blame it on my shop for losing it but we keep very meticulous records of every serial number we touch and it never came into our shop. turns out it had gone missing months before. That investigation involved a number of interrogations.
