FG-Airsoft have sent over details of their new AFS nozzles for VFC Umarex GBBR:
Nozzles with AFS (Adjustable Flow System) for VFC and Umarex M4, HK416 type GBBR (V3 nozzles versions), reference 50022
These nozzles allow you to adjust the FPS of your BBgun easily, precisely and give a very stable velocity from 280 to 390 FPS without adding cooldown (these values were measured using 0,2g BB’s, propane gas at 20°C, these values are given for information only and can vary from a BBgun to another).
Velocity adjustment is made without any disassembly, directly through the ejection port.
Testing video :