The above information came directly from a Canadian WW2 sniper with a lot of combat.
As far as the DCRA ammo is concerned, was it a SELECTED lot from regular production, as the shooters used to be told, or was it specially made. My old coach did the Bisley route 6 times and he said that it was all SELECTED from a given lot and then the boxes marked. You were DQ'd if caught in possession of ammo not from the lot selected for that year's shooting.
But it was regular-production stuff. Only the Yanks made special lots of Match ammo, and it was marked on the case-heads. Only time Canadians would have come in contact with this stuff would have been in something like the Palma match, where the host country provides weapons and ammo for both teams.