Earlier post-WWII Berettas use Roman numerals to designate the proof year. : 1945 X : 1954 XX : 1964 XXX : 1974 Common Challenges with Serial Lookups Beretta and Italian Date Marks - Blue Fieldsports
For Beretta semi-automatic pistols (like the 92 series, 84, 85, 87, 89, 90, 96, 98, and 99 series), you don’t actually need a serial number lookup to find the age. You just need to find the beretta serial number lookup best