I second the motion!
This has everything you need to know.
I would reccomend buying it before buying the rifle.
It does not cover "barrel break-in" as this is not something special to the M1A.
There are many thoughts on barrel break-in so here's one man's opinion:
5 shots, cleaning after each shot
5 groups of 3 shots, cleaning afer each group
5 groups of 5 shots, cleaning after each group.
The trick is to get that rifle clean clean clean after each shot.
Use a mild copper solvent so you can guage the fouling.
Independent of the pattern above, you will know its broken in when the cleaning gets easy.