This is some info from the S&W Forum.
http://smith-wessonforum.com/s-w-re...estion-model-10-5-3-inch-bbl-square-butt.html
Scroll down to Smithnut's post.
This is from the S&W Standard Catalog.
The Change that distinguished the 10-5 was a change to the Front sight width from 1/10 to 1/8 inch on standard barrels. Originally available as 2, 4, 5, 6 inch barrels, 3" barrels were available by special order in round or square butt and blue or nickel finish.
The 10-5 was only manufactured in 1962, as well as, the 10-4 and the 10-6. The serial number should be betweenC474149-C622699. It shows10-5 pistols with 3" barrels for the R.C.M.P.(Royal Canadian Mounted Police) and the French police with a tapered barrel, Serial #D828xxx range. They show a blued 3" barrel for the Michigan police and later adopted by the FBI.
Sound like a commercial special order.
I'm green with envy. :mrgreen: Congratulations
Dave