Try doing a google or youtube search, theres lots of websites out there. Basically a gun that fires open bolt has a firing pin that is fixed in the bolt, the bolt slamming closed fires the round, gas pressure reopens the bolt and it is held open until the trigger is pressed again. Prevents the chamber from getting to hot after firing full auto.
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats.
- H.L. Mencken