Steve; What date are you interested in. The first Riel Rebellion was in Manitoba in 1870. The Canadian Militia carried Sniders, and Colt navy's.
The second Riel Rebellion was in 1885 in Saskatchewan, with a Cree component that was in danger of spreading all over the prairies. Their field commander was a Metis named Gabriel Dumont, who later appeared in Buffalo Bill's Wild West Show. The RCMP carried their Winchester 1876 carbines in .45-75. The pistols of the Force were the 2d model Adams, which were in the process of being replaced by the .476 Enfield from the summer of 1885. It is possible that the case you refer to might be a .45-75 of the NWMP.
I am not sure of the arms of the Militia, but it is highly likely that the Snider still armed the infantry. My regular service was mostly with "A" and "B" batteries that, in 1885, were equipped with the 9 pounder field gun. There was a single Gatling Gun, used experimentally, crewed by an American officer, later nicknamed "GAT" Howard. Howard later commanded a group of Canadian volunteers in the Boer War, where he was killed in action.
In Alberta, the Alberta Field Force had a core of Militia, augmented by volunteer units such as The Steele Scouts. The volunteers were equipped with the standard arms of the western cowboy. I know that the preferred side arm of officers and volunteers was the 1878 Colt New Army.
dfait-maeci.gc.ca>