They are treating an o ring as a type of stuffing!
https://www.allorings.com/o-ring-groove-design-metric
Yes, I'm an engineer (turned watchmaker), and have designed countless O-ring seats and grooves over the years. This is not a piston type seal, which is what people often think of when they think of O-rings, and is referred to in your linked page...
It is the basically the same for face seals , there should be clearance to the side when compressed , from the top. I was lazy googling references.https://www.marcorubber.com/o-ring-groove-design-face-seal.htm
Yes, I know how seals work mate. Omega has been making this model for over 60 years, and the this and countless other case back seals are of the same design. I'm not going to argue it on behalf of all watch companies on the planet, so you do you...
Clearly the entire watch industry has been getting this wrong for decades. You should write to them all and let them know...
The only time the case back gasket leaks, is if someone installs the wrong gasket, or the gasket gets pinched when the case back is being closed. There's no design issue here, as much as you want to make one out of nothing.
I was just wondering if the genuine article might have been 0.9mm. which would be more or less ok....
Perhaps watch companies don't expect full compression from the case-back, as you would see with a bolted flange.
Change of subject. Since the lume is already missing from the minute and hour hands, getting them relumed would not impact the value to me, and it would make it more attractive. If you send it to the people recommended here, they could see that the hands are relumed nicely. But just those hands.
An argument could be made for leaving the chronograph sweeping hand alone since it has lume. But the color is not attractive (appears to be moldy) and would not match thevrelumed hands. It might be better to redo that chrono hand also. You can discuss the merits and options with the watchmakers.
Good luck and congrats to whomever you pass it on to.
Watch companies often provide a torque spec for the case backs. In fact Omega sells an add on to the Bergeon 5700 opener that is preset to the right torque, and won't let you go any further.
In my experience, I rarely feel the case back actually come to a hard stop and bottom out before already getting very tight.
