|For an overview of 5mm rounds, see 5mm round.|
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, meaning to be used effectively large amounts are often required.
- Often carried by super mutants, especially brutes and masters.
- Members of the Brotherhood of Steel tend to carry miniguns along with a small quantity of 5mm ammo.
- Lucky Harith carries this ammunition (up to 1000 rounds) when fully invested in.
- the Pitt. Found in abundance throughout
- In The Pitt, 5mm rounds can be used easily to make other ammunition types in the ammo press due to their abundance.
- When dropped, 5mm rounds have the largest containers.