The M249 is a machine gun that offers squad-level support. However, it also has a lot of recoil added to it as well so that the SMG is not made completely obsolete. In addition to decreasing accuracy whilst continuously firing the gun, the longer the player fires the gun, the M249's recoil knocks the player back a bit as long as the fire key is held down. Firing the gun in bursts increases accuracy greatly, and aiming downwards and/or crouching will greatly decrease the gun's recoil.
The M249 can first be obtained by taking it from a dead ally in the chapter Friendly Fire. If not picked up there, it can be obtained at the beginning of the chapter Foxtrot Uniform.
Headshots will make quick work of even the strongest enemies, so one should try to aim for the head if possible.
Crouching will make the weapon more accurate, so one should be sure to crouch as often as possible when using it.
Ammo for this weapon is extremely rare until the end of the chapter Vicarious Reality.
The M249 has a fairly long reload time, so one should make sure to be safe before reloading.
Tapping the primary fire button instead of holding it will greatly reduce the recoil. Moving forward removes the recoil but decreases accuracy.
If sufficient ammunition is available, the M249 can be used to impede falls by shooting downwards while falling. The backwards recoil will constantly push towards the player's back, regardless of direction, resulting in lower downwards momentum.
In some speedruns, an experienced player can "bunny-hop" and while moving backwards, they can fire the M249. The high recoil from this heavy machine gun will boost the speed of that player.
When compared to the MP5, it has a higher damage and rate of fire, only uses one ammo pool rate but eats up ammo fairly quickly, has lower accuracy, higher recoil, longer reload time and does not have a secondary fire. Furthermore, the ammo is fairly rare compared to the MP5.
All HECU soldiers using the M249 will have an ammo belt attached on their suit and a bipod on their backpack, but the model they commonly use is Gasmask Soldier and Tower's model, but there is at least one soldier that uses the Balaclava (Shotgun soldier) model, is seen at the dam.
Tower is seen carrying an ammo belt even though he holds an MP5.