When has Omega started using 3 digit caliber numbers?

Hi,

Saw a 2544-2 Jumbo, with caliber 265.
According to its serial number, it's from 1947.

That brings me to a question: had caliber 265 been introduced in 1947?
Although there are many 2544-2s with the same caliber 265, a piece of information on Timeline.watch still bothers me: "After 1949, Omega changed their movement nomenclature and the same movements have three digit caliber numbers in the 260 and 280 ranges." (https://ppt.cc/fNqwZx)

However, shown on the Omega database, CK2544 from 1951 applied 30T2 caliber.
(https://www.omegawatches.com.tw/tw/watch-omega-other-omega-ck-2544)
Which is inconsistent with what's told on Timeline.watch.




Thoughts?

According to A Journey through Time the first calibre with the new nomenclature that started in 1949 was 100 which was designed in 1941
There are others that first had an old number that was changed later on to conform to the new system like 59 8-D which became 110, 59 8-D SCS became 120 etc.
And a special mention of the famous 30T2 which became 260 etc.

Hi,
I’d actually raised the question in another thread but here may be more appropriate.....
Does anyone know at what serial point the 30T2 became the cal. 265?
Early 11M serials appear to be still 30T2’s but late 11M’s are clearly 265’s
I’ve usually worked on the assumption of approx 300k movements per year between 1947, start off 11M and 1950 start of 12M. I’ve read that the 3 digit nomenclature came into being in 1949 so did 265 serials start at approx 11.6-11.7M ?
P.s don’t you just hate the likes of the 26* movements being labelled 30T2’s in dealers adverts, or is that just me ? 🤬
Don’t get me wrong I think the 26* movements are great and an evolution of the 30T2 but they aren’t a 30T2. Hell my favourite reference runs a 267 !

Maybe up to 11.3M then so 1947-8 ?

I’ve just found this 30T2 with a serial number exceeding 11.3M, anyone seen/own one with a higher serial?