The M60 is used in the mission Compromised after Voodoo dislocates his shoulder and can't carry it. Rabbit then takes the M60 and continues to fire it. The achievement/trophy "Feeding the Pig" can be unlocked by killing 15 enemies with the M60 during the mission Compromised.
The M60 and the M60 (custom) is available for player who pre-ordered the game at GameStop and received a code, or owners of the Limited Edition or Tier 1 Edition of the game through a special drawing. It has a low rate of fire, but is countered by a high damage per bullet, low recoil, and high magazine capacity. It is available for the rifleman class.
The M60 in action.
The M60 with a Holographic Sight equipped in multiplayer.
A mounted M60 can be seen being used by the Abu Sayyaf during the rescue of the hostages during the mission in the Philippines. However, the weapon itself is not usable anywhere in the game, singleplayer or multiplayer.
An achievement related to this weapon, "Feeding the Pig", is a reference to the nickname "the pig", given to the weapon during the Vietnam War.