What gun has the biggest magazine?

Answer 1

The Ultimax light machine gun has a standard 100 round drum magazine. It's a bit of a difficult question to answer, as magazines larger than the standard have been made for a number of weapons system. For example, the 100 round Beta-C magazine uses a STANAG 4179 (M16 magazine) interface, and is thus compatible with any weapon system which uses this magazine, but it is not a standard item.

Answer 2

The P90 submachine gun has one of the largest magazine capacities, typically holding 50 rounds. However, there are other firearms, such as some drum-fed shotguns and light machine guns, that can have even larger magazine capacities, exceeding 100 rounds.