I had to drag out my Phillips & Klancher. Prior to the adoption of the Sam Browne accoutrements the revolver holster seemed to be commonly on the left. Ammunition was carried in a looped waist belt, and in 1887 a bandolier was added. With the Sam Browne gear the holster was on the right with the ammo pouch to its front, also on the right. Page 160 of Arms & Accoutrements of the Mounted Police 1873 - 1973 illustrates the evolution of the Sam Browne revolver belt from about 1890 to1963.
On the prior page, p.159, the 1969 issue revolver belt is illustrated. The caption mentions the "pouch for 6 cartridges", but to photo omits the pouch?