Gas direct, select fire describes the system of operation for which weapon family?

Gas direct, select fire describes the system of operation for which weapon family?

• A. MG3
• B. M16A2 Rifle
• C. M4/M16
• D. M4A1 Carbine

Answer: (C)

Gas direct, or direct impingement, is the operating style used by the AR-family rifles. After each shot, a portion of the high-pressure gas is routed back through a gas port into a gas tube, where it directly acts on the bolt carrier to cycle the action. That cycle is what makes the gun operate mechanically without a separate piston system. The “select fire” part refers to the ability to switch between firing modes (semi-automatic and automatic or burst) using a fire selector. The M4 and M16 families are built around this direct-gas system and feature selectable-fire capability, which is why they’re described by that combination. Models like the MG3 use a different mechanism altogether, while the M16A2 is a variant in the same family; the broader M4/M16 family is the occurrence that matches both the gas system and the selectable firing modes.

Gas direct, or direct impingement, is the operating style used by the AR-family rifles. After each shot, a portion of the high-pressure gas is routed back through a gas port into a gas tube, where it directly acts on the bolt carrier to cycle the action. That cycle is what makes the gun operate mechanically without a separate piston system. The “select fire” part refers to the ability to switch between firing modes (semi-automatic and automatic or burst) using a fire selector. The M4 and M16 families are built around this direct-gas system and feature selectable-fire capability, which is why they’re described by that combination. Models like the MG3 use a different mechanism altogether, while the M16A2 is a variant in the same family; the broader M4/M16 family is the occurrence that matches both the gas system and the selectable firing modes.