Bare aluminum uppers and lowers

[caveman74]

I have seen several online vendors selling bare aluminum upper and lower receivers.

Would using them without having them anodized or cerokoted hurt anything?

I’d be using it for a range toy and not an important AR.

[HeruMew]

Even though I have forgotten it, Aluminum doesn't Oxidize the same way steel does.

Should be fine, but may look ugly unless it's "polished" aluminum. Just bare aluminum may have some tooling marks left in it.

YMMV.

[26 Inf]

Depending on how it is applied anodizing adds some abrasion resistance.

Aluminum will surface oxidize and become a dull greyish color.

They will work, I guess it just depends on what you want.

I have heard that the dimensions of the lower and upper are adjusted to take the thickness of the anodization into account, but I don't know if that is true.

Here is what I found:

There are two types of anodizing, Chromic Anodize (MIL-A-8625E, Type 1 & 1B, Class 1 & 2) and Hard Anodize (MIL-A-8625E, Type III, Class 1 & 2). Chromic anodize is not the same as the Hard Coat anodize. The key as to what finish that is applied to aluminum AR15/M16 type receivers is the TYPE (I, IB, or III). A manufacturer may state that it meets MIL-A-8625E, but if no type is specified you don't know what you're getting. It must be type III for Hard Anodize to meet the spec for the M16. Types I & IB, class 2 can be dyed to the black or dark grey; the dye can rub off.

Type III, class 2 can be dyed and is specified on the contract drawings. Hard anodizing color will vary from light tan to black depending on alloy (this should be 7075 T-6 for AR15/M16 uppers and lowers) and can be dyed in darker colors depending on the thickness of the anodizing. Hard anodize coating penetrates the base metal as much as it builds up on the surface. This provides a VERY hard coating. If a thickness is unspecified on the contract drawings then the thickness shall be nominally 0.002" thick. The term THICKNESS includes both the buildup and the penetration. https://www.fulton-armory.com/faqs/AR-FAQs/Mil_Spec.htm

All anodizing is a conversion coating in that a portion of the base materials surface is converted from raw aluminum into aluminum oxide. In general terms, for Type III anodize ½ of the coating thickness penetrates into the surface of the parts while the other 1/2 builds up on the surface. Thus for a typical 0.002” thickness requirement, there is 0.001” dimensional change per surface. https://www.anoplate.com/finishes/hardcoat-anodize/

Based on that I don't think you will have problems with pins flying out of over-sized holes on an unfinished receiver.

If it is a range toy I'd try my hand at applying a coating of some sort. It's kind of fun to do and increases your 'handiness.' Norrell's Moly Resin is one I've used - https://molyresin.com/

There is a wide selection on do-it-yourself coatings to choose from. I'd have at it.

[GH41]

I have seen several online vendors selling bare aluminum upper and lower receivers.

Would using them without having them anodized or cerokoted hurt anything?

I’d be using it for a range toy and not an important AR.

Link us to these people that sell them bare. The only ones I have seen bare are the 80% lowers.

[adh]

can these unfinished lowers be any cheaper than $40 delivered PSA lowers.....ETA it appears the $40 delivered promo is now gone so now $49 with shipping
https://palmettostatearmory.com/psa-...fire-1728.html
the PSA lowers are totally good to go for building an AR IMO as long as you use quality parts to complete them

wait long enough and I'm sure the free freight will come back

[Artiz]

If you're building an AR just to look at and shoot every now and then, okay fine. If you're anywhere near the area of "I'm gonna use it" then forget it, it's a bad idea alltogether. If you're anywhere near the ocean forget it. Hardcoat anodizing is an engineered coating, it protects the base aluminium alloy from friction/wear and corrosion because yes, aluminium does corrode. If you're introducing an electrolyte (seawater/salty humid air, sweat, etc) bare aluminium will undergo galvanic corrosion with the steel components and will basically dissolve away. There has been NAVY guns who's barrels basically fell off because saltwater got inbetween the barrel nuts and receivers, the receiver threads weren't 100% protected with anodizing and the upper threads dissolved away with time. Anodizing is aluminium oxide, so it's HARD, however it isn't magic, it's resistance to wear verus it's hardness is dependent on the base aluminium alloy, no aluminium alloy is hard enough to prevent gouging from impacts. However 7075-T6 may be a hard alloy, but a bare 7075-T6 receiver set is going to wear at an accelerated rate compared to an anodized one. Let alone the fact that it's completely unprotected from galvanic corrosion.

Link us to these people that sell them bare. The only ones I have seen bare are the 80% lowers.

Shittiy Canadian manufacturers "cough" NEA/BCL "cough" who don't know what they're doing have been releasing bare receiver sets for sale.

[Stickman]

I have seen several online vendors selling bare aluminum upper and lower receivers.

Would using them without having them anodized or cerokoted hurt anything?

Yes, anodizing is an important part of the overall process, and it isn't about making it black colored. Anodizing hardens the surface of what is otherwise a fairly soft material. Speaking as someone who owns some ARs which are cerakoted and not anodized, the difference is obvious even living in the safe where they only get knocked into other weapons.

Cerakote does nothing realistically to make a function difference as the unanodized material can't take abuse.

I wouldn't want a knife that wasn't hardened/ heat treated. I wouldn't want a receiver that wasn't hardened/ anodized.

[caveman74]

Link us to these people that sell them bare. The only ones I have seen bare are the 80% lowers.

When I get home later this evening I’ll post links.

I don’t remember who was selling them, but I found them by searching for stripped bare aluminum AR15 lowers.

[caveman74]

Yes, anodizing is an important part of the overall process, and it isn't about making it black colored. Anodizing hardens the surface of what is otherwise a fairly soft material. Speaking as someone who owns some ARs which are cerakoted and not anodized, the difference is obvious even living in the safe where they only get knocked into other weapons.

Cerakote does nothing realistically to make a function difference as the unanodized material can't take abuse.

I wouldn't want a knife that wasn't hardened/ heat treated. I wouldn't want a receiver that wasn't hardened/ anodized.

If I were to buy a bare upper, how much would I be looking at to get it anodized?

I thought it would save few bucks with a bare aluminum upper because it would be mated to an Anderson lower and a Bear Creek barrel, nothing spectacular.


If it would cost more than buying a regular stripped upper than it isn’t worth it.

[Artiz]

If I were to buy a bare upper, how much would I be looking at to get it anodized?

I thought it would save few bucks with a bare aluminum upper because it would be mated to an Anderson lower and a Bear Creek barrel, nothing spectacular.


If it would cost more than buying a regular stripped upper than it isn’t worth it.

You need to find a good anodizer that does actual receivers, first. It's pretty much the same price to anodize one receiver or a full batch of receivers. They charge the batch of anodizing. And it's very expensive, around here just shy of a thousand bucks.