Lucifer

As OP might not answer 🙃 ... I picked up a tank, line and reg package from high pressure airsoft for £125 - see link below. That hooks up to my tapp airsoft drum mag and works like a charm my MP9. Just make sure you keep your gun lubed up and should be good to go. https://www.highpressureairsoft.co.uk/store/p73/Tank%2C_Line_and_Regulator_Package.html