The barrel nut of the TRYBE Defense AR-15 Magnite Go Fast Ultra Lightweight M-LOK Handguard w/ Cut Top Rail is 3.4oz.
I know I'm a few years late but I'd like to answer this question. The barrel nut with its two screws weighs 1.02 ounces and the handguard I bought weighs 4.05 ounces on my scale. One of the other models is lighter than mine.
3.4 Oz plus 0.2 Oz for screws say mounting hardware then 3.6