It would help a lot if you could post photos of your rifle. It would really help to identity all
the USMC features plus the unit marking on the stock.

It would seem to me that naval 1903 stocks have more unit/ship markings than US Army stocks

I have an early single bolt Rock Island stock with the number 4-99 stamp on the butt, I really have no idea why the location of the stamp or what it means -but would like to find outAttachment 92844Attachment 92843