Dennis in Az. Once again you make good sense.
I am not building an AR-10 from the DMPS crap, I am planning to use Armalite receivers, which are forged from 7175T73 or T74 aluminum.
You are absolutely correct that from the point of view of simply firing the rifle, 6061 is plenty strong. However, I am planning this rifle for more rugged use and so I think 7175 is better suited.
And 6061 is not at 95% of 7175, it's more like 50%, which is still plenty strong for benchrest shooting.
Forged is very expensive to get into initially, but once you have the equipment, it is inexpensive to run. Billet is cheap to get into initially, but it requires a lot more work which is why they are more expensive.
Forging actually strenghtens the aluminum further. I think that's desirable and 7175 does not lend itself well to billet, because it is so strong.
There is absolutely nothing wrong with 6061 billet receivers, as long as they are not in my rifles. But that's just me.
