Manual Wind Chronometers: COSC Accuracy

cazalea · 2019-10-23T10:26:51Z

Explore manual-wind chronometers meeting COSC standards. Learn about certification, historical movements, and collector pieces from Credor, Omega, and more.

Key Points from the Discussion

COSC (Official Swiss Chronometer Testing Institute) certifies approximately 1.8 million Swiss movements annually, requiring them to operate within -4 to +6 seconds per day.
Historically, non-Swiss manufacturers like Credor could receive COSC certification, but this practice ceased, limiting current certification to Swiss watches.
Key chronometer-grade manual-wind calibers from the 1940s and 50s include Omega 30T2SCRG/30t2Rg, Zenith cal. 135, and Peseux cal. 260M, known for their precision parts.
Some Omega references, like the 2364 with caliber 30T2rg, were specially adjusted for military customers or produced as 18-jewel versions, often considered 'para-chronometers'.
Independent brands like Gustafsson and Sjogren have sent Unitas movements to Soprod for tuning to meet chronometer specifications for their limited edition collections.

The Discussion

baufoam

Oct 23, 2019

Manual Winder!

I Love the 3970 !

cazalea

Oct 23, 2019

Certainly a fine and accurate watch -- certified better than COSC

I guess I opened a Pandora's box with the question asking SHOW ME YOUR MANUAL WIND CHRONOMETER which I have since retitled. (I will blame the initial wording on Amanico). To open the box even wider, only SWISS watches can be COSC certified today, but at the time it was built (1980's) my Credor Chronometer from Japan was certified by COSC before they closed the door to non-Swiss manufacturers. WHO DOES THIS ACCURACY TESTING & WHAT DO THEY CERTIFY? COSC or Official Swiss Chronometer Testing Instit

Dr No

Oct 25, 2019

I've seven, all . . .

. . . Omegas. If you include references that were either delivered to military customers with 'special adjustment', or special 18 jewel versions of the 30T2SC movement which many consider as para-chronometers, eleven. Ω ref 2364 / cal 30T2rg: Ω ref 2365 / cal 30T2SCrg: Ω ref 2366 / cal 30T2rg: Ω Genève ref 135.001 / cal 602: Ω ref CK 2179 delivered to U.S. Army, ca '45 / nickel cal 30T2SC: Ω ref UK 2292 delivered to U.K. MOD, ca '43 / nickel cal 30T2SC: Ω ref 2242, ca '44 / 18 jewel 30T2SC And I

amanico

Oct 23, 2019

The Blancpain and the G.O are very much my taste. Lucky you, Mike. [nt]

Cpt Scarlet

Oct 23, 2019

It’s all about the ritual...

cazalea

Oct 23, 2019

You already used this picture recently but I have forgotten which watch it is [nt]

Key Points from the Discussion

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