To remove all the old finish, oven cleaner works best and is the easiest, then final sand with fine grit paper like 1000 or finer to remove the least amount metal and maintain dimensions.
Ruger no longer anodizes the aluminum frames, they are powder coated. If you send to them a frame for refinish it will come back powder coated and look like new.
The only type of anodizing that will hold up is Type III or hard anodizing. The process is not suitable for the home anodizing because it takes special equipment that would be far too expensive for the hobbyist to acquire. There are several companies that will do gun parts. Here are two: http://techplate.com/firearms.htm http://www.usanodizing.com/services.htm
Moly-Resin: sprayed on and baked is tough and matches the blued steel best.
If you don't want to bake it on, Brownells Aluma Hyde II or DuraCoat are moderately good choices.
Dupli-Color High heat 1200 degrees ceramic paint gives good results but dull like the original finish.
At about $6 a can it is a fairly good substitute for the specialty paints at $20 a can. One thing about the ceramic infused paints such as this and Wheeler Cerama-Coat is that they only require a clean surface for application, (Wheeler Cerama Coat instructions state: "Blued or Parkerized steel and anodized aluminum can be coated as is. However, if any red rust, corrosion, or oxidation is present, it must be removed in order to assure proper adhesion of Cerama-Coat and to protect the substrate from further deterioration. Light surface rust can be removed using fine steel wool and a penetrating oil or solvent. Severely corroded surfaces should be stripped using a chemical stripper and/or a mechanical means such as a bead or sand blaster, a buffing or sanding wheel, or by hand sanding.")
Other products worth a look are:
Gun Kote
Norrell Moly-Resin
Cerakote
BTW: Paints have varying degrees of resistance to the various chemicals found in cleaning/ lubricating products. It best to limit (or avoid) exposure time to them. It would probably best to do a test piece and expose it to the products you use.
