The buttplate is the same one used on later O/U versions of the Sagittaire. I don't have any older Verney Carron catalogs, and don't know if there was ever a SXS with that name.
The bores measured 18.4mm, (typical 12 gauge) 9" from the breech, when it was submitted for proof. It was proofed with French powder T, and was proofed as a finished gun. The little stars tell you the chokes in the barrels when the gun was built, they may have been altered.
It is chambered for 2 3/4" ammunition.
Use it in good health.
Best,
Ted
