.
Some Canadians operating or attached to American Units during WWII were issued the U.S. M1 Garand rifle and American Equipment.
The advantages of the bolt action rifle was that it was cheaper to make, it operated under severe conditions, and it was much easier to train troops to use it. It was not as sensitive to ammunition that was needed to function, and had less operating parts to the system.
When we look at industrial capability, the United States was far ahead of anyone else at production. The question of the Sherman Tank is an example of this, along with the massive amount of aircraft built and used during WWII by the Allies, once the USA entered the war.
It is also a matter of Military thinking. The Germans, Russians and British had gone through WWI with all the mud and battle conditions just 20 years before, so that was a factor, and production lines existed to turn out the older bolt action rifles or modified versions of them. A proven system, the bolt action filled the requirements of each nation as a battle rifle.
At the start of WWII, most American troops were still armed with the 1903 Springfield rifle and the number of M1 Garand rifles were few. In fact, Remington produced a modified Springfield during WWII to augment the Garand production.
A significant change of thinking came during mid-WWII with the Germans facing mass Russian Infantry attacks, backed up by well made Tanks. The Germans started thinking about short ranged "assault" cartridges designed for 300 meters of less, and larger heavier upgunned tanks to combat the T-34.
The Swedes did develop the AG-42 semi-automatic rifle, but issued two per squad, with the rest of the squad, (except for the squad leader who usually had a sub-machine gun,) were armed with the m/96 or m/38 bolt action rifle. In actuality, most of the Swedish Infantry still used the longer m/96 rifle and the m/38 short rifle was issued to Artillery, Service and other troops.
.
