The basic load for a M249 Squad Automatic Weapon (SAW) in the Army is typically 600 rounds of 5.56mm ammunition. This load is divided into two 200-round drums and one 100-round belt. It is important for soldiers to carry enough ammunition to sustain firepower during combat operations, while also considering the weight and mobility constraints.
600 to 800 rounds
the army base
Combat Basic Load for the M16 and M4 is 210 rounds. As the M4A1 is typically issued only to select units (Army Rangers, AF Para Rescue, etc.), personnel assigned this weapon would be likely to carry more than the basic load.
They don't carry ammo in boxes. Basic load depends on the weapon system. 210 rounds for the M4 or M16, 600 - 800 rounds for the M249, 800 - 1000 rounds for the M240.
The M249 Squad Automatic Weapon fires the same 5.56x45mm cartridge used by the M16 and M4.
In some countries which field it, it's operated as a crew served weapon. However, in the US military, it is fielded as an individual weapon.
The maximum effective range of the M249 light machine gun is 1,000 yards (910 meters).
buckle means bending
FN Herstal
CLP
They could be assigned an M16A2, M16A4, M4, M249, M240B, they could be put on an M2... depends on rank, position within their platoon, etc.
The M249 light machine gun has a maximum effective range of about 800 meters for an area target.