Two RCMP (Royal Canadian Mounted Police) members mounted on their incredibly collectible Indian Motorcycle complete with side-car appear ready for action... can anyone identify their weapons and what would be the effect of firing that machine gun while the motor cycle is moving ?

Royal Canadian Mounted Police ready for action

Magnus Evenrude (first left), a member of the Reserves, participates in a training exercise on Richmond Avenue at 99th Street. The Grande Prairie Courthouse can be seen in the background.  Grand Prairie, located in Norther Alberta, was a million miles from Europe, but an invasion by the Japanese was considered a real threat in 1942 and as the Japanese were in the Aleution Islands off the coast of Alaska, the Canadians in the North were getting ready to fight.
Army Training Exercise, ca. 1942