The M249 was an exceptionally useful weapon, being a Light Machine Gun (LMG), it could be carried and operated by a single person. During the Black Mesa Incident, the M249 was used extensively by HECU forces as they made their way into the underground Black Mesa research facility. The M249 is rather inaccurate, but this is made up for by its stopping power and rate of fire. Few targets can stand against a skilled M249 operator.
Adrian Shephard availed himself of an M249 early on during the events of Opposing Force. He occasionally encountered other soldiers carrying the weapon. The weapon does not appear after the Combine invasion which suggests that it was replaced by Combine pulse technology.
- The M249 is Adrian Shephard's most powerful weapon; you can kill enemies as powerful as the Voltigore quickly by holding its fire on them. Ammunition for the M249 is scarce, so it is wise to conserve its ammo. Do not use it on weaker enemies such as Zombies or Pit Drones.
- The M249 is fairly inaccurate and holding fire on it will push you backwards. Also beware its very long reloading time. Keep an eye on your ammo and do not be caught short with it.
- An excellent way to preserve M249 ammo is to attempt to keep allied soldiers carrying the weapon alive for as long as possible. Not only will these soldiers be more effective in combat, but they never run out of ammo for the gun. Once they do die, they always leave behind 50 bullets for it.
- Despite being a machinegun, the M249 in the game only has a max of 50 bullets per belt, while in real life it can carry up to 200 bullets in one belt.