Larry,
For a decade or so, my Darne Demonstrator gun was a 12 gauge R16, marked as 76mm chambers.

They are out there. Not common.

Gene, there is not a snowball's chance in he!! that gun has original case colors. Further, and not trying to rain on your parade, the gun reminds me of a brass era automobile, that someone chose to paint with candy tangerine metallic ureathane, with a clear coat.

Unfortunate, to my eyes.

Best,
Ted