What makes these light weight? Are the recievers made if different materials?
I looked at a thinner profile barrel, lightweight BCG, lightweight handgaurd (the MI handgaurd I got only weights 9.3oz w/ the barrel nut!). Like AV mentioned ounces turn into pounds. A lot of people over look the scope and mount also. The Aero mount I went with weighs in at less than 4oz, also the butt stock setup is a big place to shave weight. I planned this build over about the last 4 months sourcing parts and researching different weights of everything. Just get a plan of what your intended purpose of the rifle is and start researching the stuff to meet that goal.