Yes, the satin gray/silver finish is a colored, anodized finish. Anodizing is great for aluminum as it creates a hard, but thin oxide layer on the surface and a hard layer of equal depth below the metal surface. In order to re-anodize, the old anodization must be removed, that means removal of the surface of the metal, hence it can be reanodized only once before the pin holes are too big to hold the various pins in their proper places. I've not done it or had it done, but a light bead blasting may not fully remove the anodizing, but might make it rough enough for a spray on type finish. Just how bad does this receiver look, it might not be bad enough to warrant messing with it. My 6906 and 6946 show some discoloration and some of the sharper edges are shiny, but it doesn't bother me as I consider these to be working firearms, not collector pieces.

__________________
VCDL, GOA, NRA