Storm Shadow:
Your Model 10-10 .38 Military & Police Heavy Barrel was probably manufactured in early 1992. Guns in the BKZ2xxxx range shipped in February of that year.
mr.e moose:
Your gun is probably a .455 Mark II Hand Ejector 2nd Model manufactured for Britain or Canada between 1915 & 1917. This was a Triple Lock without the ejector shroud. Check the rear face of the cylinder. If in the white, or lacking a serial number, it may have been machined to accept .45 Colt after the war.
If it lacks the 3rd lock at the yoke, then its a .44 Hand Ejector Second Model made sometime between 1926 & 1940, in an unlisted caliber. That would probably warrant a factory letter from the S&W historian to verify its provenance.