AR Lowers Material ???

[morrcarr67]

OK, I'm gonna start working on my AR pistol finally.

I've been looking around and seeing some different material listed. Some are made from 6061 stock and others from 7075. Some also list T6 behind both the 6061 and the 7075 numbers.

What's the difference between them?

Is one material easier to work with? I just have a drill press to work with.

Is one better than the other for a pistol build?

[Clipper]

The T6 is the hardness. Mil spec forged lowers will be 7075. Billet lowers may be either, more commonly 6061 it seems. 7075 is stronger if the two are dimensionally the same.

As far as machining, i don't think you will notice a difference on a drill press.

Some will argue 7075 is way better. I would like to see them wear out a 6061 one.

[morrcarr67]

The T6 is the hardness. Mil spec forged lowers will be 7075. Billet lowers may be either, more commonly 6061 it seems. 7075 is stronger if the two are dimensionally the same.

As far as machining, i don't think you will notice a difference on a drill press.

Some will argue 7075 is way better. I would like to see them wear out a 6061 one.

Cool.

Is T6 the standard hardness?

[ddk1]

T6 is sort of the hardness. It signifies what heat treatment the aluminum went through after forging. There are other heat treatments available that are less common.

http://www.matweb.com/reference/aluminumtemper.aspx

[Rocketrob]

7075 is signifigantly stronger than 6061.
6061 is a weldable alloy and has a somewhat softer surface and does not machine as cleanly.
7075 is signifigantly more expensive than 6061. The lowers I have seen machined with 6061 price do not reflect the savings that the fabricator is reaping.


6061
This is the least expensive and most versatile of the heat-treatable aluminum alloys. It has most of the good qualities of aluminum. It offers a range of good mechanical properties and good corrosion resistance. It can be fabricated by most of the commonly used techniques. In the annealed condition it has good workability. In the T4 condition fairly severe forming operations may be accomplished. The full T6 properties may be obtained by artificial aging. It is welded by all methods and can be furnace brazed. It is available in the clad form (“Alclad”) with a thin surface layer of high purity aluminum to improve both appearance and corrosion resistance. Applications: This grade is used for a wide variety of products and applications from truck bodies and frames to screw machine parts and structural components. 6061 is used where appearance and better corrosion resistance with good strength are required.

7075
This is one of the highest strength aluminum alloys available. Its strength-to weight ratio is excellent and it is ideally used for highly stressed parts. It may be formed in the annealed condition and subsequently heat treated. Spot or flash welding can be used, although arc and gas welding are not recommended. It is available in the clad (“Alclad”) form to improve the corrosion resistance with the over-all high strength being only moderately affected. Applications: Used where highest strength is needed.

[morrcarr67]

Very interesting. Thanks for the post.

I'm pretty sure I've found my lower, and it is one made out of 7075.

[Palmaris]

Pretty much all materials are good for lower, including SLA (3D printing, some guys tried and worked for a while). But, there is a reason for military standards existence. I would recommend to stay with Mil Spec stuff-forging 7075 T6, finishing and hard anodizing plating (Type III). Do not get confuse with hard anodizing, true Hard anodizing Type III only available in 2 colors- clear and black. Any other color is not Type III.

[morrcarr67]

Pretty much all materials are good for lower, including SLA (3D printing, some guys tried and worked for a while). But, there is a reason for military standards existence. I would recommend to stay with Mil Spec stuff-forging 7075 T6, finishing and hard anodizing plating (Type III). Do not get confuse with hard anodizing, true Hard anodizing Type III only available in 2 colors- clear and black. Any other color is not Type III.

That's good to know too. I did see one vendor advertising a DFE lower to match Magpul's parts.