FTR, I�m no metal smith but, I�m pretty sure that all the forged aluminum parts are cheaper to produce. Forging is a process in which you take metal (in this case aluminum) melt it down and pour it into a mold, and then you take it out and machine it into what you want. That being said they can use scrap aluminum and that is why it is cheaper to produce also there is less machining with forged parts as opposed to billet parts.
I agree that when someone wants to sell you something they will tell you anything to get it done. (I.e. Billet parts are the best). What you are saying about Armalite is right also hence AR (Armalite rifle) but, the term has now morphed into a catch all phrase.
As far as which is the best, you would have to go to a metallurgy book and look up the properties of the aluminum I.E. 7075/6061 because those numbers mean how much pure aluminum is in the part, 70% 7%, 5% or 60%,6%, 1% along with other alloys that are in it (chromium, vanadium Ext.) Then determine what is needed for your purpose.
We won�t go into heat treating and the machining process as that will take a long time. Also my explanation on the numbers for the aluminum and alloys was short and to the point but by no means comprehensive. Have a nice night:)
