Are ULE bodies 6061 or 7075 aluminum?

[Pneumagger]

I have an idea that requires welding and if the bodies are 7075, obviously I can't weld it.

[BigEvil]

Both. There are ones that are 6061 and some of them are 7075.

[Pneumagger]

Any way to tell?

[Newt]

Try welding it.
:D


Seriously though, the only other way I know is to try anodizing it. 7075 will produce a bit more smut, while 6061 anodizes just about clean. An experienced machinist will be able to tell when cutting it as well. It's gummier. I don't know a non-invasive method though.

[Pneumagger]

In my experience, 7075 machines nicer than 6061.
7075 has the same heat conduction with a stronger part and harder surface.

[Newt]

Correct. 70075 is much harder and has a higher machinability rating. It chips nicely, 6061 makes ugly stringie things that would belong on some sick, demented Christmas tree.