Click the link http://www.airsoftforum.com/board/AEG-Internal-Parts-t179019.html
Most of you will ask why do I post guides and tips from ASF? Well for starters I don't have to type and compile a list when they're plenty of well written threads on ASF. Second, All the threads from ASF are valid and make a good point. Why re-write something that already explains it all.