It's an Alex Henry left-hammered falling block in .450X3 1/4, 52 guage. From all indications, Serial, Barrel, and action numbers, plus proofs, it would run 1868 to 1874, but the serial may not be Alex Henry's due to "Robt. Lees" both on the barrel and the side of the action. "Alex Henrys patent14--" is under the forearm on the barrel. Front of the action is stamped "52". Which "Perth" is Lees attributed to, as there are several spread around the world? ~Arctic~