[Hectic]

8Well its all prety much been said, sorbo mostly changes the tone or muffles/dampens the impact so the sound isnt as sharp and doesnt carry as much. You can build a prety quiet aeg, especially at indoor velocities but its a combo of piston head, cyl. head, sorbo thickness and stiffness, spring strength, piston weight, shimming, gear quality, motorand motor height, even plastic vs metal body, full stock etc..
I have this cyma mp5sd6 i built, its prety quiet for sure.
3/16 soft sorbo directly on the stock rubber, pom piston head, swisscheased lonex red piston, stock motor, 13:1 shs gears, bearing bushings, shimmed nicely verry little slop, m90 spring
edit: i should add its also quiet because its pushing 30rps so response time is fast so the cycle doesnt last long enough to create alot of sound. Tho it is still not loud on full auto