no.1 RAS systems usually fit on any marui compatilble AEG but i think AEG and GBBs have different parts, im not too sure
like which ris system were you thinking about to put on what brand gun??
no.2 you can get the barrel anywhere its not a restricted item
http://www.airsoftpost.com/matrix-st...d-p-28513.html
and lol did you take 5 tequila shots in between questions?