learning about this stuff is almost as fun as being able to take it out and shoot it...
Lot of history to learn with these old mil-surps.
I would clean your metal with 0000 steel wool and Eezox. The Eezox cuts rust better than anything I have used in fifty years. Go light with the elbow grease and you should have a very nice patina when done.
This started off rusted with some light pitting.