the earlier BHP, the serial numbers are on the right side near the ejection port for the slide numbers and the top edge of the frame above the triggers, later they moved them to in front of the grip frame ( grip strap) and the 60's and 70's guns the first single digit number in front of the 'letter' was the year it was made ,around the late 70's I recall they used a 3 digit number (245??) then letters and more numbers.....harder to know the years of mfg, after that, need a reference book...........
the 60-70 vintage guns came in a black zipper pouch, with a red lining. This was the desireable era guns, especially with adjustable sights as they were 'true" Belgium made guns, later the parts were Belgium but assembled elsewhere...........hope this helps
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