Sorry to give a dick answer - but its something called the search function. "ICS SRC M4" yields this one as a pretty good place to start: http://www.airsoftcanada.com/showthr...hlight=ics+src
My advice - in order to not get flamed incessantly on ASC, don't ask questions that have already been asked and answered. Look it up first, and make sure there is no other thread out there already addressing the same or a similar topic. Glean what you can from that thread, and if you need further clarification, ask for it then. Just asking "which gun is better" won't get you much respect of resident ASC flamers... though "which gun is better, ICS or SRC" means you've at least skimmed the surface of your search for an M4. Keep plugging at it (by using the search function, first)!