5.56mm Round (Fallout 3)

The 5.56mm round is a type of ammunition

Gameplay
The 5.56mm round is the third most common small guns ammunition found in the game, compared to the .32 caliber and 10mm rounds. After The Waters of Life quest, the 5.56mm cartridge becomes more common as enemies will use assault rifles more often than hunting rifles chambered in .32.

Weapons using this ammunition

 * R91 assault rifle
 * Chinese assault rifle
 * Xuanlong assault rifle
 * Infiltrator
 * Perforator

Locations

 * At Fort Independence, Brotherhood Outcast Casdin will trade technological items for 5.56 rounds, stimpaks, frag grenades, or RadAway.
 * 14 magazines spread throughout Metro Central, of which four near a female Talon Company merc behind a wrecked train in the waiting area.
 * Four ammunition boxes in the Arlington Public Library lobby, just to the left when entering.
 * Three boxes in the Super-Duper Mart, next to the Protectron terminal in the storage room.
 * Completing the quest Free Labor will unlock the ammo press. Located in The Mill of The Pitt, the ammo press converts any ballistics-based firearm ammunition or scrap metal into any other types of ballistic firearm ammunition, including 5.56mm.