5mm Round (Fallout 3)

The 5mm Round is a Big Gun-only ammunition in Fallout 3. 5mm is traditionally belt-fed, and is available in rather high quantities, something made necessary by the notably large "magazine" sizes on the weapons that use it--for example, the Minigun loads 240 rounds at one time and fires an exceptional rate, requiring that the player carries a huge supply if they intend to rely on miniguns.

Used in

 * Minigun
 * Eugene

Locations
Generally speaking, the 5mm Round is the most common big guns ammunition found in the game, as Super mutants- especially Brutes and Masters- tend to favor the Minigun. By spending time in various areas of Washington, DC, particularly the bunker area found near the Washington Monument, the player can acquire 5mm rounds quickly. Members of the Brotherhood of Steel tend to carry Miniguns as well, and with their alarming death rate outside Galaxy News Radio, it's possible to get some 5mm rounds here as well.

5mm rounds are made somewhat obsolete if the player finds a Gatling Laser. On the other hand, these are hard to keep repaired to full condition, making 5mm weapons a good backup weapon. If the player has The Pitt add-on, 5mm rounds can be used easily to make other ammo types in the Ammo Press due to their abundance. Lucky Harith also carries this ammunition (up to 800 rounds) when fully invested in.