OKay,

not a mettalurgist by any means.

I understand that uppers and lowers are made from Aluminum, and that after being cast, milled, or forged, and finished... they are anodized for hardness and wear.  Does the anodizing actually add and strength to the parts or is it just for exterior wear?

I'm asking because if you have a lower or an upper that has serious markings or blemishes on the outside (not the inside) is it okay to bead blast, or sand it down and then either "leave it in the white" or just paint it?

Since the inside will still be anodized there wouldn't be any problems with the wear and tear correct?

As long as I don't mess with anything on the inside everything should still be fine...right?

Thanks...

Functionally it will be fine, but if you blast or sand away the anodizing the surface will be softer and more prone to scratch/wear. Painting is just an exterior coating, anodizing changes the surface of the aluminum.

Leaving the aluminum "in the white" is not really a good idea, since exposure to body salts and the elements will cause it to oxidize.

You can have a receiver re-anodized or you can just coat it with one of the many refinishing products on the market.

Personally I would just leave it alone and use the hell out of it.

Quoted: OKay, not a mettalurgist by any means. I understand that uppers and lowers are made from Aluminum, and that after being cast, milled, or forged, and finished... they are anodized for hardness and wear.  Does the anodizing actually add and strength to the parts or is it just for exterior wear?

Anodizing is a process to protect aluminum from corroding (oxidizing) and to provide the finish a little protection from wear.  It doesn't add any strength to the aluminum.

I'm asking because if you have a lower or an upper that has serious markings or blemishes on the outside (not the inside) is it okay to bead blast, or sand it down and then either "leave it in the white" or just paint it?

Bare aluminum will oxidize in air, producing a white, chalky oxide coating on the metal. While not particularly attractive, it does protect the metal from further corrosion. Unfortunately, handling would probably wipe off the coating, starting the oxidizing process all over again.

Painting works alright, but be sure to get paint made for use with aluminum.  There usually is a prepping process to ensure the paint sticks to the aluminum.

Since the inside will still be anodized there wouldn't be any problems with the wear and tear correct? As long as I don't mess with anything on the inside everything should still be fine...right? Thanks...

Right.

Get yourself some Norrels Moly resin, it will take care of any surface treatment issue after you remove the blem's.

Everything previously said is all true, However...

Dude, this is your rifle. Do you like it? Are you going to keep it?

Be proud of your guns. Spend a few bucks to have it bead blasted clean and re-anodized properly. It will look professional, and you'll sleep at night instead of worrying about corrosion.

Like the others have said, your gun will not fall apart by next week if you don't do it. So once you finish building it and it's complete, then have it refinished with something nice. Think of it as the last part you buy. Cheers.

Send it to US Anodizing.  They do the retro lowers and uppers to match in XM gray.  Im sure Victor (I think that's his name) could put you back in the black again for low dough.

www.usanodizing.com/pricing.htm - Anodize an upper to good as new = $50.