I've finished out a few 80% lowers. One of them being a 308 lower. Has anyone fired one of their 80%'s without the hard coat annodizing? Just duracoat/ceracoat,  and fire away?

ETA: my receivers were raw aluminum.

I Cerakote them just so they are not raw aluminum

Depends on how you intend to use the rifle.

If you're plan on getting dirty with your rifle and it gets tossed in the dirt here and there, I would want it anodized. Then spray painted. But everyone treats their ARs different.

Yes.

I got an 80 finished out in SOCAL before they cracked down on CNC nonsense.

That lower has had few K live round through it and a few K sims through it.

I use mine pretty rough.
Found a local metal finisher that does Type 3 hard coat anodizing

Proper Type II is indistinguishable from Type III without lab testing. Lots of places can do good Type II including at home in your garage. If anyone has any doubts my buddy took one of his DIY anodized lowers to a commercial anodizer for testing. They said it was the best they had ever seen, with a full 0.001” thickness. (most anodized products are only done to get enough thickness to take dye).

Either get that done or Cerakote or Duracoat.

Bare Aluminum does "rust"  corrode over time.  White powder forms and that  is the sign of it.   That's why aluminum case ammo has a clear coat on it.

I doubt it will cause any problems for you due to the receiver being so heavy and thick

Local anodized says I will need an FFL to transfer it through.

Been looking at home anodizing.  Doesnt look too hard at all.

Huh? FFL transfer to anodize it?

Yeah. First email from them just said it needed a marking to denote it as mine. Got ready to take 2 finished lowers and it changed to FFL to transfer them through.

Looking at DIY anodizing. Doesn't look like too involved a process.

Has anyone done any home anodizing? Been looking at a few 30 amp power supply's to do Type 3.
Any variable power supply's that do a good job but aren't $400+ ? It will just be a hobby type set up.

Here's my anodizing process. It took some time to piece this together. I haven't done the color step yet and used gunkote instead. I'm going to try the black dye from Caswell next time.

Shopping list:
¼” aluminum rod 36”. I used a die set to put ¼-28 thread on one end so it could be screwed into the pistol grip screw hole on the lower. This rod can be reused since there is no anodizing build up at the threads. Snug with pliers prior to anodizing. Also cut shorter 4” pieces off the rod and thread to use as handles when doing other steps so the part is not touched.
Battery charger - I used an older 4 amp 6/12V. I was trying without success to find a reasonably priced rheostat for adjusting voltage and then gave up and just started at 6V for 5 minutes then switched to 12V for the remainder of time. In my case the amp gauge pins at max for a few seconds when first turned on, then settled down to rest at 2A @ 6V and about 3.5A @12V.

H2SO4 - Sulfuric Acid - Autozone had QT size and O'Rielly's had Liter. Same price but the QT is slightly larger. Mix 2 QT's into 1 ½ gal DIH2O.

HNO3 - Nitric acid - pH down by Tetraflora – bought this from a local hydroponics store for $9/QT. After a lot of research, it was the cheapest way to get nitric acid. Nitric Acid was the most difficult chemical for me to find at a reasonable price. You only need 10% for the desmut step. You can also wash/scrub the lower again in dish soap and get most of the smut off, but if you want to do textbook, use HNO3.

Lower anodizing  procedure:

Do not let part dry anytime during the anodizing process steps 1-4.
1.One day prior to anodizing - Add 1 part battery acid (H2SO4) to 3 parts DI H2O. Slowly add acid to H2O. 2 qts battery acid, 1 ½ gal DI water. The solution needs to cool down before anodizing.
2.Degrease – materials: dish soap, Purple Power or Greased Lightening, acetone
Wash with Purple Power, rinse tap water, wash with dish soap, rinse tap water then DI H2O rinse, dry, soak in acetone 10 minutes. Dry
3.Etch – Red Devil Lye 2 tablespoons per gallon DI H2O. 120g/L
-Attach AL rod to lower to use as a handle.
-NaOH bath 2-5 minutes, agitate every so often until a greyed/blk.
-Spray DI H2O to rinse off over NaOH bath.
-DI water bath covering lower, agitate, pour off and change water let soak for a few minutes.
4.Desmut – 10% Nitric Acid bath (Techniflora pH down)
-3-5 minute turns white. Agitate in bath.
-Spray bottle with DI water
-DI water bath covering lower, agitate
5.Anodize
-H2SO4 should be at 69° - 72°F, use glass aquarium thermometer.
-Use air stone with aquarium pump to circulate the bath.
-Replace short AL rod on lower with longer rod for anodizing.
-Battery charger - Negative (cathode) to lead/AL in bath, Positive (anode) to AR lower AL rod.
Start at 6V for 5 minutes (mine held at 2A). Switch to 12V for remainder of time (mine held at 3.5A).
Read amperage and calculate time.
If power supply reads 3.5A:

720/3.5 = 206 amp min  
81 sq in/144 in/ft = .5625 sq ft  (81 sq in is the lower surface area)

206 x 0.5625 = 116 min in tank @ 3.5A

Spray bottle with DI water over tank
Soak in DI water, change water soak several minutes
Dry several days before Gunkote process

Thanks. I really appreciate it

Glad to help.

One thing I added was placing the anodizing tank (5 gal bucket) in a large plastic storage container and filling the storage container with some water and a little ice to keep the acid temperature from rising during anodizing. I use 2 large chunks of lead on the cathode side so it helps keep the 5 gal bucket from floating in the storage container.

Definitely need to do this if anodizing lower one after the other because of the temperature rise caused by anodizing.