Mlr224,
That manual may have been translated by Frenchicon personnel, the use of the name Mousqueton being typically French.
In 1943, some of the units of the French army operating out of North Africa were equipped with US hardware, and the need for written instructions in French must have led to the translation of many US manuals.

Patrick, thanks for the reminder.

Cafdfw, I also happen to own a dropped M1icon carbine, a Saginaw SG that was air delivered to the French resistance in Brittany during the winter 1943/44, my wife grandad made good use of it at the time.