Been looking at Ranfft but cant tell. Anyone care to help I'd be pleased.

 

I would guess cal 23M or 27M. What is the size of the movement?

 

A bit hard to measure excactly, bit more than 23 mm

 

OK, I guess that answers it, since it's apparently not 27mm. Should be quite obvious from Ranfft. You can also ask the Longines archive folks, assuming they're working.

 

Even without the measurement, it's a 23M.

 

Agreed. The alignment of the click and the case screw give it away for me.

 

Didnt see one with the same regulator

 

Here's a few with the same regulator:

https://forums.timezone.com/index.php?t=msg&th=1031044&rid=0


http://chronocentric.com/forums/chronotrader/index.cgi?md=read;id=83844


These regulators seem to appear more often on the 23M center-seconds variant like the one above. I couldn't tell you what the technical difference of the regulator is though. Maybe someone more knowledgeable could chime in.

 

Different regulator, different shock protection. It's the same movement.

 

Is that an age sign, quality or neither or something else

 

We are talking about an era where shock protection was becoming more common, so earlier movements are more likely to be unprotected, and after a certain point nearly all Longines movements had shock protection. But there may also have been a transitional period where shock protection was selectively added to higher end watches. I haven't made a detailed study of it.