If you find yourself fighting lesser-equipped factions such as the FIA or other rebel groups who do not have extensive access to body armor, this is usually a good choice because the ammo is much lighter to carry than 6.5 or 7.62 NATO, so you can have more rounds in your kit, and the weapons have rather low recoil and good control.
This means that lighter armour like Tactical Vests are usually fine to shoot through but heavier plate or military standard armour can be trouble to get through. Generally Assault Rifles (slightly heavier and slightly more accurate/ less bullet velocity) or Carbines (slightly lighter, slightly less accurate/ less bullet velocity) are your general use weapons and are most effective at closer ranges, with within 100-350M or so is considered 'close range' in Arma.ĥ.56 NATO and 5.8 calibre Assault Rifles are lighter and handier compared to the larger 6.5 rifles but the rounds they fire (5.56 NATO Ball) are not very effective against anyone wearing Body Armor greater than about LvL1/ LvL 2.
