Molcom Korean Airsoft does some tests and overview of the E&C HK416A5 DE AEG. This AEG is fully upgradeable with a standard V2 gearbox and comes with trades. The rifle uses E&C’s QD1.5 system, which allows for easy spring changes without the need to remove the gearbox from the lower receiver. To access the QD spring guide, simply remove the buffer tube and twist the plug. This makes it easy to customize and maintain your rifle.