A most interesting example as it was proofed in the Zella-Mehlis proofhouse in November 1911 but carries "Eagle" "Nitro" (as well as the "mm" stamp) which was as per the 1912(post 1910 Suhl) rules. The "SS D" is actually "SS" and "D" possibly for Sylv. Schilling and the brothers Denecke(?) who were sourced for parts, would be my guess for now. The other "SS" on the left side of the rifled tube also would be for Sylv. Schilling pretty much noting he made the gun. What's the name atop the rib? I'd guess a value between $900 to $1500.
Kind Regards,
Raimey
rse
