The perfect ageing process for a seamaster 300 Alain. Sorry if my question came across in the wrong way, it was never meant to be critical.
I do know people who have gone by the 21mil movement serial number which in my experience with the sm300 is not reliable as all 3 i have owned, .014 and .024 have had 23mil serial numbers. That is the only reason i asked.
I have been very lucky with my 1964 collection as apart from a couple of pieces all my Omegas have -64 after the reference number. Also all my single and double crown super compressors have the month-year code and both my Rolexes have quarter-year codes.
Other companies are more difficult which is why i have several english cased gold watches. You cant argue with an assay mark :)
Best
Graham