This might help some of the people who have a Sig and want to take down the gun for whatever reason.
I fun this neat sig 552 take down tutorial from 858 Airsoft during my research on the SIG 552, as I am planning to install a metal body on mine. Hopefully this will help other people too.
I don't know where to put this, so I guess I'll put it here. Feel free to move it or PM me to repost it at the correct location. Enjoy
I just found the spring upgrade part.