Ammunition

Ammunition is something that every non-melee weapon in the game requires to use.

Overview
For most guns, the primary type of ammunition are bullets. While in real life, different guns use different calibur bullets, in Combat Arms the ammo is universal by weapon class.

For explosive projectiles, each weapon has its own special type of ammunition. The M32 Grenade Launcher, for example, fires explosive grenades - while the M32 Incendiary Bomb and M32 Stun Grenade fire completely different types of ammo.

For grenades and other explosives, each item counts as "ammunition". An example would be the M16A1 AP Mine, where each individual mine counts as ammo.

Melee Weapons
For obvious reasons, melee weapons do not require any ammo to use. Therefore, they are the only weapons in the game (aside from the RMS-12 Flamethrower) to have unlimited uses. They are also, therefore, the only weapons in the game that you cannot have more than one of at a time, since there would be no point in having multiple melee weapons.