Winchester trigger housing marking

I found this Winchester trigger housing which is the early type with the small hole (before the cloverleaf hole came into production). What is interesting is that it is also stamped CM.

Anyone else seen one of these early trigger housings stamped CM ? nothing listed in Canfield's book "The M1 Garand Rifle" Attachment 86488

Here are two from my collection. These may be slightly later, as they don't have the "-" between the drawing number and the "WRA." Not sure on that, though.....they obviously have the small hole, however.

Attachment 86687

Attachment 86686