Here is a good video on how the AR-15/M16 platform works, for those who are just learning about them. This video goes in depth on full auto, semi-auto and 3 rd burst. Explains the reason the bolt assembly twists and a brief history of the sights. The only thing it doesn't cover is piston based systems, just covers GI only.
*edit* Guess it would help if I posted the link for the video eh?
*edit* Guess it would help if I posted the link for the video eh?