I’ll bet no 78 pound kid would be able to carry that very far in his left hand.
Is that the best you can do???
You're asking someone to make a lot of calculations in their head in a short amount of time. An airsoft AK weighs 5.7 lbs. A real AK, loaded, weighs a little over 9 pounds. That's a little more than a gallon of milk.
I'll wager you this isn't an Airsoft, and this kid totes it all day long.