The Negev is a gas-operated automatic firearm that uses propellant gases from the barrel to cycle a short-stroke gas piston operating system under the barrel and a rotary bolt locking mechanism. The bolt itself features 4 radial locking lugs that engage the barrel extension and its rotation is controlled by a pin on the bolt body, which rides inside a camming guide machined into the bolt carrier. The bolt contains a spring-powered casing extractor unit, while a lever ejector is housed inside the receiver (it is rotated by the recoiling bolt carrier).
The Negev’s adjustable gas regulator has three settings: “1” – used exclusively when feeding from a magazine (the weapon’s rate of fire in this mode is 850–1,150 rounds/min), setting “2” is used in normal operating conditions when feeding from a belt (rate of fire: 850–1,150 rounds/min) and setting “3” which is used under adverse operating conditions, such as in the presence of dust, dirt or heavy fouling (cyclic rate of fire is 950-1,150 rounds/min). Early prototypes used a different 3-position gas adjustment system: setting “1” – normal operation, setting “2” – for adverse environmental conditions and setting “3” – isolates the gas system, used to launch rifle grenades with the use of a grenade-launching blank cartridge drawn from a special 12-round magazine (from the Galil rifle).