Garand barrel number, dots, and squiggles

[Sea Buck]

Have a new toy a Springfield Armory M1 Garand. Ser No: 5857xxx. The barrel stampings are :
SA/-F6535448 8 55 A220A and surrounding the number code are various other stampings; LL ll/. r. P 7 in a box. Can anyone decipher this for me? The SA and the 8 55 means Springfield Armory Aug 1955 ? What does the rest of this very interesting number code, and dots and squiggles mean ?

[Dfariswheel]

The numbers are a drawing number, which other people call a blueprint number.
That the blueprint to which the barrel was made.
At various times during production, the M1 parts were changed. Each change got a new drawing number, which was stamped on the part.

The "dots and squiggle" stamps are factory inspectors stamps and have no meaning outside the production plant.