"Weighs only six pounds"
These days you're lucky if you can find a 16" carbine that light, and it'll have one of those ridiculous fake collapsing stocks, but will also still probably have a heavy barrel.
Most postban ARs have a barrel heavier than my FAL. Your typical 20" HBAR-15A2 weighs in at around eight and a half pounds.
But, this was back before they tried to turn the AR-15 into a full sized battle rifle, and used it for what it was, a light weight small caliber rifle.