SHobbs,
I checked my Collecting the Garand, by J. C. Harrison. Your 2. 9 Million S/N puts this receiver as being built "June 1944 to September 1944". He states in the preface that the M1 was made 1936-1957. One of the interesting books to look for is the NRA M1 reprint, lots of history, servicing, accurizing and match shooting info.
I have not been hit with M1 Thumb yet, knock on wood, but it would be a memorable moment.
These don't like to be babied, the OP ROD slams the bolt home to battery, that's what it needs, don't ride the OP ROD and ease it into battery.
The only slight trick to field stripping is rolling the OP ROD of off the bolt, when you see the secret step over toe hold required, it's a piece of cake. Virtually NO FORCE REQUIRED!!!!!!!!
En Bloc clips are still available all over the shows and via the supply houses.
If this is your first experience with the M1, let these guys know and you can get some great experience opinions here, if you carried one for US, please excuse me for stating any of the obvious to a Veteran.
Enjoy it!