Thanks for your input LeFusil. BTW, You've shared some excellent photos on Wrist Breaker in your earlier posts. Much appreciated!!

I would have guessed that using metrics in chamber stamp took place somewhat later? Here is a photo of the engraving on my gun. I took some photos quickly with my mobile yesterday, and the quality isn't too good. Sorry for that.

The "case length" text seems original... Well, kind of, anway. Of course it could have been added later, but why engraving and not a stamp?

As regards the C or LC in the diamond, at least Nigel Brown in his British Gunmakers vol. 1 p. 427 says in referring to the period 1887-96 that "initials LC indicated a long chamber of at least 3 inches."

It's good to hear that style of striker discs sounds original. The retaining screws are already flush with the fence surface, but I just have to examine it a little bit further. Unfortunately I don't have the gun at hand right now, and I'm not able to provide any further info on the details.

Regards,
Sakari