From aluminum block to 1 piece AR Lower

Viking2721

Viking2721

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I'm not sure where this conversation originated, or who posted it for that matter. All I remember is a conversation that was based around how cool it would be if the GG3 could mill a solid 1 piece lower.....apparently cool has become reality.
Screenshot_20231115_173952_Facebook.jpg
 
OK, this is cool and all that, but how is it better/faster/easier/cheaper than an 80% lower/jig/router?
 
no4mk1t said:
OK, this is cool and all that, but how is it better/faster/easier/cheaper than an 80% lower/jig/router?
Click to expand...

Oh, it's slower and much more expensive (to buy the mill). But you don't need an 80% receiver, which may or may not be outlawed. You can go from a 0% billet to a working receiver. That's very cool.
 
Racer88 said:
Oh, it's slower and much more expensive (to buy the mill). But you don't need an 80% receiver, which may or may not be outlawed. You can go from a 0% billet to a working receiver. That's very cool.
Click to expand...
OK, 80% is currently GTG.
Buy however many you might think you'll need in the future and be prepared.
Anything may be outlawed when the political winds blow that way.
 
no4mk1t said:
OK, 80% is currently GTG.
Buy however many you might think you'll need in the future and be prepared.
Anything may be outlawed when the political winds blow that way.
Click to expand...
I'm all set for a good long while! LOL!

But the notion of being able to mill a receiver from a solid 0% block... very very cool.
 
Racer88 said:
I'm all set for a good long while! LOL!

But the notion of being able to mill a receiver from a solid 0% block... very very cool.
Click to expand...
Me too. Just saying, being prepared can take two avenues...
 
They are improving their product. Now they can get the entire lower inside the mill instead of doing it in multiple parts.

While working from a casting or forging of the lower and just doing the finish machining will be cheaper, working directly with the raw stock is nice to have in the tool-box of options. You also could choose another material to work with... like Derlin or Lexan plastic using the same process.

We are currently in no danger of loosing access to 80% aluminum forgings, but we have lost a few companies that generate the demand for forgings that allows 80% ones to be available at such a low cost. With every Anderson or Del-Ton that goes out of business, we loose a vendor who was willing to have the raw forgings made, partially machine them, and sell the ones excess to their needs to us hobbyists. It takes volume to justify doing the forgings and we are a tiny little sliver of that volume. We get them just because adding some extra ones in a paid for forging run cost pennies per part to do. Alcoa could forge 50,000 lower receivers only if someone is willing to pay the cost per piece to do it.... otherwise, they will use that capacity to knock out wheels for tractor trailers. They don't care either way.

So, yeah... having the blueprints and cad cam files out there is a positive move, just in case.
 
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Reminiscing a little here: It is really great how far this hobby has come in twenty years.

When I did my first lower, it felt like I was buying parts from a shady dude selling counterfeit watches out of the trunk of his car.. "Pssst, hey buddy, wanna buy an AR?" Really it was just raw Cerro-Forge forgings from a sub-contractor (Advance Ordinance in Daytona) and jigs welded together in someones garage shop. Over-run product from a DPMS contract that otherwise would have been written off as scrap aluminum at the end of the run. That is how our hobby got started. That's how it worked back then. Three or four major AR manufacturers ordering thousands of castings or receiver blanks, and the excess being hawked on the market in various side hustles to the few who wanted to "roll their own".

Now look at us.
 
So, AR15 lowers are forged from 7075-T6 aluminum.
Some of you engineers out there may chime in about how a forging is stronger than billet if size is the same, due to the grain structure of the metal being compressed in the forging process.

So how much does a piece of billet 7075-T6 big enough to make a receiver cost? Does anyone know?
Are those making a 0% lower from billet using this alloy, or something else? The T6 part of the specification is important. Is the billet they are using been subject to the T6 tempering process?

You can buy an unmachined AR lower forging for $25 ea. here. They are calling it a 20% lower.
It would seem you would be ahead of the game going this route in machine time and added strength of the forging. Engineers, yea, or nay?

www.80percentarms.com

20% Lower - Blank AR-15 Lower Receiver Forging

This 20% lower receiver isn't a complete lower, hence the name! Pick up this 7075-T6 aluminum machined blank AR-15 lower receiver at 80 Percent Arms.
www.80percentarms.com www.80percentarms.com

For the pros and cons of the different metals AR lowers are made from, read this.
www.gunbuilders.com

Cast vs. Billet 6061-T6 vs. Forged 7075-T6

You see it everywhere: "6061 T6 billet", "7075 T6 forged". What does it mean? What about cast aluminum? This guide compares all three and their properties.
www.gunbuilders.com www.gunbuilders.com

If I were the one wanting to whittle lowers from scratch, I would buy forgings. Probably get a quantity discount if you get like minded peeps to go in on a group buy.
 
7075 alloy is stronger than 6061 but not as easily machined nor weldable. For this application either will work fine... :)

PS: I have one of those 20% as a paper weight. :)
 
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Any of the above are acceptable for an AR lower. Commercially made AR-15's were originally cast and forged types. Some companies (ahem, Schutzen/Olympic) had some failures with their cast ones, with most of the issue being the buffer tube ring. The same problems the resin cast and 3d print community experince now. The cost of forgings dropped so that became the standard that all of the companies use, but you could still use a cast one and get a usable lower. The basic requirements of the material to retain its shape while the rifle is being used are pretty low. (They increase when the rifle is given to a bunch of teenage boys who might use it as a club, a rung for a ladder, or a pry-bar instead of as a rifle ;) )

Carving the lower out of bar stock is a bit of over-kill from a structural point of view, and kinda wasteful in terms of materials and total machining time. The flip side is you get to create the shape that is different from your competitors. If you want to differentiate your product from everyone else's, you go down this route. The cost of making the dies to forge that custom shape is a multi-thousand dollar investment. So, milling from bar stock makes sense despite the higher cost-per-piece. Also, the ability to make it from something other than aluminum, like one of the engineering plastics.

Just doing some quick pricing (using Online Metals)... for a block of rectangular aluminum bar stock, 1.75" x 6" x 12" of 6061-T6511 Extruded comes in at $119. A similar sized bar of 7075-T651 is $347. So, it is not cost effective to machine the lower out of stock. You have to order enough raw stock to drive the price down to something a little more reasonable, or obtain the aluminum as cut-off scraps from some other project. It only makes sense if you are just making a few of them and you cannot start from a existing casting or forging of the part. Or, you are just bloody-minded enough to want to do it regardless of what it costs (Ok, I've done that, guilty as charged ;) )

edit: The prices are off their online quote sheet. You could probably find the material from some other vendor for less. I just went to them because I have purchased from them in the past, they are reputable, and they give you a copy of the ASTM cert for the chunk of metal you bought.... it may still be chinesium, but it is at least up to the expected mechanical properties of the material you are paying for.
 
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The bottom line seems to be if you want a lower for the lowest cost to machine yourself, go with the $25 20% lower.
If you are chasing styling points, and want a wild and wooly skull lower, bar stock.

Personally, rather than some wild and crazy machined lower, I would opt for some artistic laser engraving on the blank slate that is both sides of the mag well. If you want to get fancy, have the engraver set the laser to cut the design .005 into the metal rather than just turn the anodizing clear, and then color fill it as desired.
 
no4mk1t said:
The bottom line seems to be if you want a lower for the lowest cost to machine yourself, go with the $25 20% lower.
If you are chasing styling points, and want a wild and wooly skull lower, bar stock.

Personally, rather than some wild and crazy machined lower, I would opt for some artistic laser engraving on the blank slate that is both sides of the mag well. If you want to get fancy, have the engraver set the laser to cut the design .005 into the metal rather than just turn the anodizing clear, and then color fill it as desired.
Click to expand...

Yup, that about sums it up. The absolute cheapest "roll your own" in the current market is to start with a casting or forging. Now, you have to do some of the really hard machining (like broaching the magazine well) yourself using a 20% lower, but it is do-able. That's the lowest cost of raw material, but with a lot of labor you have to do yourself and some special tooling.

That's just the way the market has gone. The absolute lowest cost for a completed AR lower is going to be a commercially made one.... right off the shelf from an FFL. All the work is done, no tooling required, but you have to do the permission slip from the gubberment.

80% castings or forgings split the difference. More expensive than a 100% ready to use lower, but with easier final machining steps and a lower number of specialized tooling. (Not everybody has a broaching press available... you are not going to find one at the local big-box store. ;) ) The market settled here on the 80% as the best balance of material, labor and tooling that a D.I.Y person can handle without the gubberment permission slip.

And milling from bar stock is the most expensive path. You have to buy both the raw stock, and you need the equipment to work it. However.... and this is a big however.... once you have the equipment, you have the means to make one should the other options get closed out. Some folks value that bit of self-reliance. I do too. I just can't justify buying that custom CNC mill.

Personally, I'm at the saturation point with the AR.... I think I probably have a lifetime supply of lowers. The last few I bought were not because I needed them, I just wanted to give some support to a vendor (TM in DeLand) who was fighting it out with the gubberment.
 
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This ad was from GB. I'm not sure how old it is or was. I've got a 2024 date on the pic but I think it is older than that...

0percent1.JPG
 

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