My nickels worth. As stated before, CoS muskets ordered before 1775, tended to follow the Brown Bess pattern. The "GR" cypher was missing from the lock plates, but I've seen pictures where the name of the colony was engraved on the butt plate tang or barrel.
Maybe I'm splitting hairs, but to my mind the CoS were disbanded or rolled into colonial militias after the start of hostilities. After this, I'd call them "battlefield salvage" muskets.
Were French locks used? Most certainly so. But, so were Hessian, Dutch, English, and locally made locks and furniture. A musket sporting a French lock with a Brown Bess barrel, with a mixture of furniture stocked in ash would be not only correct but very interesting.