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"This 12-gauge combat shotgun is fully automatic and drum-fed. Great for blasting holes in walls and possesses surprisingly low recoil and muzzle rise."
— In-game description

The ACS12 is a shotgun featured in Tom Clancy's Rainbow Six Siege, introduced in the Operation Para Bellum expansion. It is available for use by Maestro and Alibi.


The Auto Assault-12 (AA-12) is a shotgun developed in 1972 by Maxwell Atchisson. The current 2005 version has been developed over 18 years since the patent was sold to Military Police Systems, Inc. The original design was the basis of several later weapons, including the USAS-12.

In-game, designated as the ACS12, this shotgun boasts the highest round capacity of any shotgun in the game. Though slow, the ACS12 also features a fully-automatic firing mode. In addition, the default iron sights are identical to the MP7 in that they obstruct vision minimally when aiming down sights.

The weapon works like an automatic DMR thanks to the slug rounds, but the relatively slow TTK at distance calls for precision shots by aiming at the head of the target. However clocking in at 59 damage is enough to downright kill Light Armored Operators and Medium Armored Operators in two slugs, while a third is needed for Heavy Armored Operators. Situationally, the weapon may be effective against enemies at half health and below. Same as the TCSG12 and the BOSG.12.2, the slug rounds of the ACS12 have high destruction and low damage dropoff, making it useful for both creating rotations and lines of sight.


  • High single shot damage
  • High destruction capabilities
  • Low recoil


  • Very low rate of fire
  • Low overall damage

Weapon Attachments

Under Barrel



  • The ACS12 in-game may have been modified to shoot from a closed-bolt configuration, since the bolt is always forward at rest.
  • The charging handle is not pulled back far enough during a full reload.
  • The real-life AA12 does not use 30 round drum magazines, but rather 20-round and 32-round. 
  • With the release of Operation Steel Wave the ACS12 was converted to slugs rather than pellets and also featured a weak damage output that was later 'buffed' to 59 points of damage. 

Patch Changes

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