Fine, "Some of the 30L chronometer grade movements have a subtly different balance cock and overcoil hairspring compared to the standard 30L, but no fine regulator." In case you missed his post, @gatorcpa was asking about modifications to chronometer-grade movements.

 

Yes, my point being that early in the 30L’s production the movement did have a variation, but later in the 30L’s run there would have been no identifiable difference in the movement between a chronometer or non-chronometer 30L. I have a 30L chronometer movement that does not have a Breguet overcoil or truncated regulator arm that was confirmed by Longines to be correct. Absent the dial, it appears to be a standard 30L. This is because the Breguet overcoil was eliminated in ~1959.

So, to get back to the OP, it wouldn’t surprise me at all that a watch produced by Longines in the 60’s would have chronometer on the dial (and actually have been chronometer certified) but have minimal or no discernible movement features to support that.

 

Yes, I read your thread, and I understand that you own a 30L chronometer without the modified balance. It's an intriguing case, but as far as I know it is the only example that has surfaced, compared to dozens of 30L chronometers with the modified balance, including all the watches described on longines30l.com, and known to the collector who runs that site. I assume you will update your thread as you identify other 30L chronometers without the modified balance.

 

That is incorrect. According to Havi, who runs Longines30L.com, he was familiar with examples of these movements prior to me unearthing my example. The below is from a conversation we had in 2017, when I found my 6691 with a Breguet overcoil that is not chronometer certified. I hope he is ok with me posting this for context.

 

That's interesting, but still sounding like second-hand rumors. Obviously, it is easy for regular 30L movements to be swapped into chronometer-dialed watches, and I'm sure that has happened more than a few times for repair purposes. So anecdotes aren't so convincing. Please post movement photos and extracts when you get them. Many of us would love to see a dozen or so.

 

Ok, here is some "archival" information from an earlier correspondence with Jennifer Bochud of Longines, to help shed some light on the 30L/LS chronometers. Note that her responses are confined to the 30L and LS movements, and do not apply to the automatics that are being discussed on the main thread of the OP.

Note also that the excerpt is from several years ago, but I have had no reason to check to see whether any of her assertions were subsequently revised. I have italicized my questions, and emphasized the most salient parts of her responses in bold type.

 

Thanks all for the added info!

I dug up the information I received in the extracts from Longines for the three watches I posted. Two interesting bits:
1) While #1 and #2 were invoiced in July & Oct 1965, the serial #s are only 305 numbers apart (both 1285*).

2) For #3, which was invoiced in Sept 1966 and has a serial of 1346*, it had a note from Longines that it was shown in their archive to be a 9044 reference, which is a date at 12 variant with a different case style. Perhaps there was a movement swap on this one, which would explain why the serial isn't close to the other two.

So - perhaps there was a batch of chronometre-rated movements with 1285*ish serials?

I'd greatly appreciate if anyone is aware of others to provide more data points!

 

I wonder if the movements that Longines produced had a specification in terms of expected daily variation in different positions. They may not have advertised this but I wonder if the watchmakers had an idea of what to expect in terms of performance for each calibre before it left the factory.

If there are no noticeable differences to a regular 291, perhaps it suggests what the movement can be regulated to.

Just a thought.

 

Another one of these popped up on Yahoo Japan. Sold for about $700 + shipping/import duties.

This one is the most patinated one I’ve seen. You can hardly see the rail track facets from the front, but they’re visible in the second photo below.

If someone dreamt these up, it happened a long time ago. It’s a good sign it showed up in Japan as well (where the others were delivered).

 

Another one of these popped up recently - added as #5 in my original post. Serial on this one is 12'849'746, very close to the first two. If they made these with consecutive serial numbers, that’s at least 1,380 of them.

https://www.ebay.com/itm/2554926952...pREckSIRLG&var=&widget_ver=artemis&media=COPYPurchases made through these links may earn this site a commission from the eBay Partner Network

 

I like the brand, and I like the dial and caseback, what else can you ask for in vintage . I'll let the experts speak to the other items. Wear and enjoy this one!

 

Adding another one sold on Yahoo JP today.. nice bracelet too

 

May as well add some macros..

 

Very good deal..

By the way, I’ve updated the original post with archive info for two of them (five total with archive info now). Definitely a recurring theme with delivery location and time.. so I’m speculating they were a special order.

 

Hi,
Just sharing some of my collector's experience I have with Longines chronometers, it doesn't seem to have any straight rules to distinguish an actual chronometer from standard production movement by eye. Like Rumar89 showed, chronometers made before 1960 usually had an overcoil, but there were already some exceptions, like the 30LS : I've never seen the center second variant of the 30L with an overcoil, chronometer or not. The 28x/29x family doesn't seem neither to ever had have an overcoil, even in the earliest examples of the late 1950s. Only movements older than the 30L always had an overcoil in their chronometer version (like the 12.68Z or 22AS). But some non certified movements also had the overcoil, so it was impossible to distinguish movements only on this feature (the 27.0 for example looked the same with or without chronometer certification).
Some chronometers had an inscription about temperature and positions adjustements, but no rules again, 30L chronometers never had these, some late 22AS and 27.0S for north american market had them, the 280 chronometers I've seen had those as well but not the 341, this last being made in the early 1960s like the 28x/29x and having no visible distinction between its chronometer and standard version. Only the later 431 seems to always had those inscription in the chronometer version.
Concerning micrometer regulators, as well no clear rules. While they were extensively used for their pocket chronometers, none of the 1950s wrist size had one to my knowledge. All the 34x and later 43x family had one, but I don't recall having ever seen one in the 29x family, while the 28x had two different types (swan neck and eccentric screw). I'm doubtful the rotor would allow enough space for the nice swan neck of the 280 chronometer.

Most of the time, what really sets apart chronometer from non chronometer movements is the use of higher grade materials, mostly for the hairspring and barrel spring, but the naked eye can't judge those.

Now here's another 291 chronometer from this japanese site, the movement seems identical and goes for the non-visible distinction with standard version :

https://www.tokei.blog/longines/26909

 

Added a 7th to the list.. owned by our very own @WatchHeaven44