Nice rifle.

As for the small markings, I believe they are arsenal marks. Not the same as the big one by the serial number but still signifying where the part was made. They should all match. I can't be sure of this as they are not mentioned in my available book but it is something that was pointed out to me when I was seeking a dust cover. It is possible to match the three digit serial number every 1000 but they also have these small marks which would also need to match.