The M163 Vulcan is a self-propelled air defense gun system mounted on an M113 tracked vehicle. It uses a 20mm six-barrel rotary machine gun, the M61 Vulcan, capable of firing up to 3,000 rounds per minute to counter low-speed aircraft and drones. Currently, it is also used to support ground combat, delivering high destructive firepower as demonstrated by Thailand during operations to reclaim border areas encroached upon by Cambodia for over 40 years. The system was employed to bombard Cambodian military strongholds along the frontline at Prasat Ta Muen in Surin Province; at Hills 225, 350, and 677; at Chong Samed; at the Khao Phra Wihan frontline in Sisaket Province; and at Ban Khlong Paeng in Sa Kaeo Province.
Full name: M-163 Vulcan Air Defense System (VADS).
Main weapon: 20mm six-barrel rotary machine gun (M61 Vulcan).
Rate of fire: Up to 3,000 rounds per minute.
Firing range: Maximum approximately 4,500–5,000 meters.
Platform: M113 tracked personnel carrier.
Role: Originally for air defense; currently also used to support ground fire.
Use in Thailand
The Royal Thai Armed Forces have effectively deployed the M163 to support ground combat, especially during past border conflicts, causing significant impact on targets.
The M113 personnel carrier equipped with the M61 Vulcan 20mm machine gun, which fires at 3,000 rounds per minute with a maximum range of 4,500 meters. The popular Army Military Force page reported that Thai soldiers adapted the M163 self-propelled air defense system with the M168 Vulcan six-barrel 20mm rotary machine gun, firing up to 3,000 rounds per minute, to bombard and attack Cambodian military bases at the frontline. This created overwhelming suppressive firepower causing severe destruction—wherever it was fired, it devastated the target.
High rate of fire
The M61 Vulcan’s six barrels deliver intense firepower (up to 3,000 rounds per minute), creating a "massive curtain of bullets" that can strike targets both on land and in the air. It effectively shoots down low-flying fighter jets and quickly destroys lightly armored vehicles.
20mm ammunition: Its 20x102mm rounds have high destructive power, especially later model armor-piercing discarding sabot (APDS) rounds that can damage tank tracks, gun barrels, or key components of tanks, despite limited armor penetration.
Air defense effectiveness: Highly suitable for close-range air defense. The M61 excels at shooting down helicopters and low-flying jets, especially within 1–1.5 kilometers, and can decisively intercept advancing enemy forces.
Infantry support: Its ability to suppress and attack ground targets makes the six-barrel M61 valuable in infantry support roles, notably during the Vietnam War, as noted in The National Interest and War Thunder Wiki.
Limitations:
Effective range: The M163’s effective range for air defense is limited, with the explosive fragmentation (HE) rounds having a self-destruct range of about 1,800 meters.