What type of ammunition does the M249 squad automatic weapon use?

The M249 squad automatic weapon is designed to use 5.56 mm NATO ammunition. This caliber is specifically chosen for its lightweight characteristics, making it suitable for automatic fire in a squad-level weapon, providing soldiers with a high volume of fire while maintaining portability. The 5.56 mm rounds are fed into the weapon using a disintegrating link belt, allowing for greater ammunition capacity and a more streamlined feeding process. This feature is essential for the role of the M249 in providing sustained fire support within a squad during combat operations.

The other types of ammunition listed, such as 7.62 mm, 9 mm, and 12 gauge, are not compatible with the M249. The 7.62 mm is typically used in heavier machine guns, the 9 mm is used in pistols and submachine guns, and 12 gauge is for shotguns, highlighting the specific use and ammunition requirements of different weapon systems.