6061 uppers?

[Ridgerider]

According to the description on Midway, the DPMS Lo Pro is made of extruded 7029 T6.
I don't know the specifics, but it is probably closer in properties to 7075 than 6061.

Now I am really confused because when I searched Midway for the DPMS Low pro 4 listings came up 3 complete uppers and a lefty upper receiver all the upper descriptions state this "The Lo-Pro Upper Receiver is constructed of 6066-T6 aircraft aluminum and is of the "Slickside" variety," the upper receiver just says Product Information
Stripped upper receiver ready for a left hand build. Lo-Pro Flattop is streamlined and has no forward assist or dust cover. Stripped left hand bolt included. Now also on that page is What others have bought there is this Product Information
Shop more DPMS products This DPMS Low Profile Flat-Top AR-15 Stripped Upper Receiver is constructed of Extruded 7029 T6 Aluminum and given a Hard Coat Anodized Finish for durability.

So with that in mind are we really getting the truth from any manufacturer or distributor with the materials used in their construction. Or are they hedging their bets and covering themselves and use whatever material is available at the time. What I do know is this that any aluminum upper or lower whether it be 7076 6061 or 7029 it will be stronger than any injection molded plastic with a little bit of carbon added.