Powder coating aluminum

[AlHunt]

I'm placing this question here because it doesn't fit in S&W Gunsmithing, since it's not specifically a S&W.

I have a raw (unfinished, not anodized) AR lower I'm thinking of powder coating. I've had such fun powder coating my cast bullets that I'm thinking of doing the lower. I tumble the bullets and would do the same with the lower, if it'll work.

As most of you know, AR lowers are aluminum. Doing the bullets, I hit about 380F degrees for 20minutes.
BUT ... will the 7075 aluminum anneal and lose hardness at that temp? Or could I water quench it?

Actually, anodizing looks like a fairly easy thing and I'm thinking of taking a run at that.

I'll appreciate anyone's thoughts.

[Ivan the Butcher]

Why not ask customer service of the Lower's manufacturer?

Ivan

[scooter123]

Anodizing provides a ceramic layer (Aluminum Oxide) with a hardness estimated to be between 70 and 80 on the Rockwell C scale, which is very hard. Unanodized Aluminum is quite soft, so comparing the two is sort of like comparing ebony to balsa wood. Obviously most would prefer an Anodized finish, after that is done you can powder coat any color you desire as long as you pay attention to the curing temps.

As for material properties you have to heat 7075 aluminum to 775 F in order to anneal it, so anything under about 450 degrees should be just fine.

[flintsghost]

There are two types of anodizing. Hard Anodizing is very hard as stated but standard anodizing can virtually be wiped off a gun frame. One thing about anodizing is that there can be no steel parts on the frame at all as steel will totally destroy the anodizing bath. Therefore the ejector and pin, plunger tube and all 4 grip escutcheons have to be removed from the frame when anodizing. This is one reason that neither Colt nor S&W will refinish alloy frames in revolvers or semi auto's. In powder coating the metal must be absolutely clean and in order to assure that all steel parts are bead blasted washed and wrapped in plain brown paper to preserve the cleanliness till the powder is ready to be applied. Then the powder is sprayed on and finally baked in an oven. Bead blasting will spoil the anodizing.

[Gunhacker]

You also need to take into consideration what the thickness of the power coat will be after curing it, it might be better to consider Cerrakote, lest you end up needing to drill out the power coating in pin holes, etc in the lower to get things to fit.

Give the Brownell's tech guys a call at 800-741-0015 and run this by them.

[AlHunt]

Thanks, the 775 annealing temp is what I needed. Good information here and I appreciate it.

I'll look in to the cerrakote, I hadn't really thought about that one.