Simple solution to that flimsy, feather-light shell of your ACTLabs guns.
Simply fill in the handle area with this expanding Foam called "Great Stuff"


The foam is non-conductive, adds a little weight and keeps the gun from "Creaking" when you squeeze it in the heat of the moment shooting foo's.
Open up the gun and squirt a
LITTLE AMOUNT of the expanding foam inside the
GRIP AREA ONLY, then close her back up, after an hour or less, the cavity should be filled.