Yep.

[Linked Image from photos.smugmug.com]

The original proof was likely 1887-1896. 1896-1904 would be marked 1 1/8 oz Max. 1904-1925 1 1/8 oz Shot
Some of the previous proof marks were over-stamped with NITRO PROOF 1 1/8 oz. The large 12 over C in a diamond is from the reproof.
The gun was originally proved at 13/1, was honed (thereby 'spaining the mirror .739" bore) and then reproved at 12/1

The wall thickness numbers are critical regarding choosing the appropriate loads.
ed is well aware that today we can easily reproduce the pressures of the black powder loads actually used when the gun was manufactured.