(Click to enlarge.)
The majority of the revolvers acquired by Canada were never marked in any distinctive way, and no completer record of serial numbers is known, so it is not possible to definitively confirm Canadian military provenance for most of them. However, based on the serial numbers of the thirty or so known examples of these revolvers which eventually got stamped with an "M.D." mark, it is known that they were all manufactured in 1883, 1884 or early 1885. Mine was made relatively late in 1883, is the correct configuration for a Canadian Militia revolver, and was located in Canada, so it "fits". I am awaiting a Colt Factory Letter which will hopefully confirm that it was shipped to Hartley & Graham, the New York outfitter that supplied them to the Militia Department.
For anyone who might be interested in additional information, here are scans of the entire chapter on the Canadian Militia revolvers from "Colt's Double Action Revolver, Model 1878", by Don Wilkerson: