 Some firearms, like the AN-94, AO-63 assault rifle and the G-11 have a feature in which rounds are fired in quick succession (2-round burst at 1800 rpm in the case of the AN-94).This increases the burst's accuracy, as multiple rounds are fired before the recoil impulse has affected the shooter's aim (before the impulse is even transferred to the shooter, in the case of the G-11).This is performed by having the barrel slide back and receive another round in the chamber pulled by a pulley and is fired as the barrel slams at the bolt, when the first chambered round is fired when the sliding barrel is at rest, as opposed to a cam mechanism of the M16 design.