Photos of the Russian markings on the top of the barrel rib on S&Ws, and on copies made by the Russian arsenals ( Tula,etc.) and by Ludwig Loewe Co. in Berlin, are shown is the "Standard catalog of Smith & Wessons, 3rd, edit, by Supica & Nahas, and in "Smith & Wesson 1847-1945" by Neal & Jinks. Your gun is probably one of the Tula or Loewe guns. Ed.