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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. It was introduced in the Operation Para Bellum expansion and is available for use by both GIS Operators.


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, as well as a fully-automatic firing mode. In addition, the default iron sights are similar to the MP7 in that they obstruct vision minimally when aiming down sights.

While exceptionally potent for soft destruction, the ACS12 is notoriously weak for combat, thanks to the relatively low fire rate and damage output.

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.

Patch Changes

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