What do most people do to coat their raw lower after milling? I have looked at home anodizing which looks a little more involved than I want to get. Cerakote/durakote I dont really want to mess with either. I dont want to send it off and pay someone either, I want to do whatever I decide. There is Aluma-Hyde 2 paint, but does the lower have to be coated with something before applying or will spraying it directly to the raw aluminum be sufficient?

I've often wondered if you could dunk it in Alumablack. I've never heard of anyone doing so, though.

I was under the impression that if u don't coat them they will rust or be brittle. If that's the case then I may leave one raw and buy a raw upper. I bought 3 from Tactical Machining today so I'll have some options.

I've done three, one billet, two forged.  All three are all black otherwise.  Billet is going on two years and still looking good.  Forged are newer, but no different than day on

Aluminum does not rust, but can corrode an leave a white substance. 7075 is corrosion resistant, and can be left raw if needed. Type 3 anodizing which colors the aluminum a straw yellow before it is dyed makes a layer on the surface on the aluminum that makes it more scratch resistant, and a little harder than the aluminum itself, and it is why lowers and uppers are anodized. It protects the aluminum a little more. Paints don't generally do much, but ceracoat is pretty hard stuff, and does add a layer of protection. Is it needed? It is really up to the end user. Raw 7075 will outlast you generally. One area where it does help is the fire control group pin holes, and it helps prevent egging of the holes. KNS pins can prevent that so the coating or anodizing is a non issue now.

can I just use spray paint like I have on my regular lowers and the paint adhere just as well to the raw aluminum? I'm not too worried about scratches, my rifles get used. I think it gives them character, but I don't the paint just chipping off under normal use because it's not sticking to the raw metal.

I have, Some have a nice sponge camo on them after they get milled. East to touch up, and easy to remove with carb cleaner if you don't like it and want to switch it up. I use the camo paints, and do a clear over the top when done. Doesn't chip like you would think it would. It wears nice. I have one that has a 3 year old camo on it and it looks great! A little wear on the grip, and the brenton bump, but it does not look cheesy at all. Black may be another matter.

Like I said, I use spray paint on all my other rifles and I know it holds up fine for what I need it for. Just wasn't sure how the paint will take to raw aluminum. Guess I'll just do it with one and see how I like it and how it holds up. If not I'll do a home anodizing and paint afterward.

I use Alumahyde II, it holds up well for most any common gun cleaners and oils.

Degreaser

Use Norrell's Moly Resin or Cerakote shot from a cheap Harbor Freight airbush and baked on to cure.  Conventional spray paint is not durable enough.

maybe you can clear coat it. when i was into cars i was powder coating alot of stuff. you could powdercoat it clear or have someone powdercoat it clear for you. personally i would send it to dan_gray to have it cerakoted. he does great work at a great price. he charges $60 for a lower, $90 for an upper and lower or $130 for and upper lower and forend. i had him do my upper, lower and forend in patriot brown and it came out great. turnaround was about 3 weeks.

could you use a toaster oven to bake it? if you could get a cheap toaster oven, the harbor freight airbrush and do it yourself on the cheap.

My buddy and I both made our 80% lowers at the same time.
He left his raw and it seems to be holding up well.
Granted our climate is kind to metal.

I went with a Lauer dyi product:
http://www.lauerweaponry.com/index.cfm?fuseaction=category.display&category_ID=929
It turned out to be very easy to use and very nice looking.
How durable is it?
Dunno, ask me again in ten years.