I am looking at a circa 1940s 9mil Cal. 27 CHRO chrono but the inner back has me a bit stumped, as I don't recognize these sorts of reference numbers and it is also sterile with regards to any Omega branding or the usual nomenclature.



Would anyone happen to know whether this could be a genuine Omega way of marking the inner back for a Cal. 27 CHRO model during this era?
Thanks in advance for any info & best regards,
T.

 

I have the 174-something stamp on an Omega cal 321 chrono inside case screwback from the early 50's....But it also stamped Omega and Swiss Made in the normal way. IIRC the 174- stamp is also used by others, maybe Tissot, I can't remember with any certainty, but a little Googling may shed some light.

How does the rest of it look?

 

Yes, the 174 reference number is also seen on Tissot chronographs using the CH27, but always with the Tissot shield.

 

And here mine from 1950/51



Pre-clean obviously

 

Thank you both for your courteous and informative replies.
The rest of the watch looks good albeit I think with later-style "stick" 321 chrono hands instead of the period correct "kite" style.
I was also thinking that it might have been a later Tissot back used in a pinch but now I doubt it, as apparently those were also marked with their trademark. I have a request out to another collector with the same style chrono (down to the dial) so maybe there will be a blank inner back match there.
Could it be unstamped due to being an earlier WWII or pre-war production example??
An odd duck to be sure though, as you both point out, the reference number is the correct one and also the correct style of stamp. So I kind of doubt any kind of outright fakery despite the mystery.
To be continued, hopefully, and thanks again,
Tom

 

This Lemania chronograph has an unbranded caseback similar to yours:
https://omegaforums.net/threads/lem...cal-2520-ref-174-original-box-and-band.28851/

I have seen a number of early Tissot chronographs (based on the 15TL family) with Lemania casebacks, so this may have been a not uncommon practice at the factory, perhaps if production got caught short of branded casebacks. Or perhaps your caseback was damaged and was swapped out for a fresh one at a service long ago.

 

Certainly makes sense, though obviously the Lemania linked is about 10 years later than the Omega in question give or take. Also the extra 3 numbers atop the inner caseback that I posted are a bit confusing.
Thanks again,
T.

 

Perhaps maybe the caseback was simply replaced on said watch when the original became too damaged or just unusable?

It would be a good explanation, provided the rest of the watch is legitimate and not a fake or frankenwatch.

 

My first thought is that there was an original caseback with a (deep) inscription that was swapped for a sterile one direct from a generic supplier later in the watch's life.

Pure supposition but it's the simplest reason and I like simple explanations.

 

Sure of course it could be.
I was just checking to see if there were any precedent for an original period correct Omega back without their stamp. Also if it were replaced by Omega I would still expect to see their stamp especially by the 50s or later. So a Lemania replacement back makes the most sense if there is no such thing as a non-signed Omega (or Tissot) one.
Cheers,
T.

 

The number 174 refers to the Lemania case reference. All of the SSHI (Tissot/Omega/+) chronographs was made by Lemania (as in cased and delivered complete). For some reason there are Tissot and Omega variants in circulation using the Lemania case ref.
Normally Omega and Tissot would have their own ref numbers stamped. I have also seen variants with double stamped references (Omega/Lemania).
Please note that Lemania used case reference numbers, and not model references like Omega. Due to this one can find a large number of variants (dial/hands/movement) with the same case ref.

Here is an extract from a 1956 Lemania catalog showing ref 174. (A=Acier - Stainless Steel, Etanche:Waterproofed-round pushers):


Cheers!

 

A Lemania ref 174 was sold here on OF back in 2015:
https://omegaforums.net/threads/lem...cal-2520-ref-174-original-box-and-band.28851/

 

This makes perfect sense, thanks. So I wonder if that top number inside this caseback "430" is an Omega reference or in fact what the hell it is?
Best,
T.

 

I believe the Omega reference version of Lemania 174 is 2451
Note the lugs.
Hope that helps.

 

I think that maybe wishful thinking, I don't ever remember seeing a genuine Omega case that didn't Omega written on it somewhere. I think as @Northernman said most likely a Lemania case back.

Does the rest of the watch resemble the Omega 2451 or 174 / Tissot 174 / Lemania 174 references? They all have quite a distinctive case design.

 

Yeah I certainly think replaced back is the likeliest scenario. Just wondering if there was an earlier pre-4 digit system especially for what is essentially a re-branded Lemania, as Northernman confirmed.
As for resembling those correct models I believe it does...


Cheers,
T.

 

The watches I have seen with that dial have had french aeronautic case backs if I remember rightly, it could be one of those watches with a replaced case back?

 

Sorry F.A.I Federation Aeronautique Internationale
https://www.vwcltd.com/portfolio-item/omega-2451-f-a-i/
http://www.mwrforum.net/forums/showthread.php?75691-Omega-27-CHRO-FAI

Might be of interest too.

https://www.fullywound.co.uk/produc...onograph-vintgae-1944-wwii-pilots-chronograph

 

Yes! That makes sense to me, especially as an owner down the line might not have like the engraving. Or a watchmaker swapped it out for a "cleaner" one. The outside of the back I posted is sterile as far as I can tell.
Thanks also for the links -- had just Googled that MWR one.
Well done, Michael, & cheers,
Tom

 

As to the 430 marking I have no real clues.
I have seen, especially on earlier, waterproof cases, that backs and cases were paired. If so I would expect to see a similar number also somewhere on the case. Back side of lugs, or between lugs.