Hi again everyone,
I have a question which originated with what I noticed on a few vintage Tissots built with a 27B movement, however I don't believe the question is at all specific to Tissots.
In many of the watches I've seen online, a "tabbed" retaining ring has been used rather than what appear to be two empty screw holes where you would have thought the movement would have been secured to the watch case. Examples of these can be seen in the first three pictures, all different watches but all with relatively early serial numbers:
I have also seen the same movement secured using the screw holes I'd have expected to have been used:
However looking for more examples of this, I noticed this method of attachment only seems to be used on serial numbers great than 300,000. This of course could just be coincidence, but I still find it curious.
I've seen similar rings on other vintage watches. They certainly do lack the polish of using the inset screws to secure the movement, but are they a result of after-market repair, or fitting a watch to a case it didn't originate from? The holes were clearly made in the early movements, but I'd have thought if these were examples of after market repairs then pictures of this tabbed ring would be the exception rather than the rule for earlier watches.
Does anyone have any thoughts on this?