If you get mesmerised watching slow-mo videos on YouTube, here is one for you. Gaosen Kinetics did a slow-mo of a Tokyo Marui Hi-Capa 5.1 Gas Blowback that has a cut-away firing...
A quick test of the fully licensed Umarex G28 Gas Blowback Rifle made by VFC in this Taktik Airsoft video... "Simple test video of the Umarex G28 GBBR by VFC. We wanted to calibrate the sights to make the airsoft as accurate as possible. This was asked by the client so our techs proceeded with calibrating the hop up with optic."