Don't bead blast... that will remove the anodizing. No, the gray finish is not anodizing. The gold tint (or silver) under
the gray finish is the anodizing. Anodizing makes the surface of aluminum harder and corrosion resistant. Aluminum
corrosion looks like white powder or sugar.
Wash the bodies in a sink of warm water with a little detergent and a bottle brush.
Set aside and let dry.
Floorplates can be sprayed with Krylon "Semi Flat Black", which is more an eggshell finish. Looks and holds up better
than Flat Black.
Spray the body with Moly Disulfide Dry Lube. That's what was originally used on those mags.
Reassemble with USGI green, or Magpul anti-tilt followers and new springs. I would not bother replacing the USGI green
followers, but the original black followers need to go.