This chamber is designed for using AEG inner barrel.
Recommended precision length as below:
Real Shock Version - 430mm
Pro Sniper Version - 430mm
G-Spec - 300mm
PSS10 Bull Barrel 450mm - 300mm
PSS10 Bull Barrel 575mm - 430mm / 300mm while using biuld-in Silencer
PSS10 Bull Barrel 700mm - 550mm / 430mm while using biuld-in Silencer