A semi or fully automatic firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear. When the trigger is pulled the bolt goes forward, feeding a round from the magazine into the chamber and firing it. Accuracy can suffer somewhat in an open-bolt design, but this is generally less of a concern in automatic weapons.
These guns include: BAR, Bren Gun, Carl Gustav M/45, CETME Ameli, FN MAG , FN Minimi, Hotchkiss machine gun, Lewis gun, M3, M60, MAC-10, MG34, MG42, Mk 19 grenade launcher, MP40, PK machine gun, PPSh-41, Sten, Sterling, Suomi M-31 SMG, TEC-9, Uzi
An "Uzi" is an open bolt machine gun.