M231 Firing Port Weapon

Compact M16, 5.56mm: Port, Firing, M231
M231
TypePersonal defense weapon
Carbine
Place of originUnited States
Service history
In service1980–present
Used byUnited States
WarsGulf War
Iraq War
Production history
Designed1979
Produced1980–present
VariantsNone
Specifications
MassEmpty: 7.34 lb (3.33 kg)
w/30-round magazine: 8.34 lb (3.79 kg)
Length28.25 in. (71.76 cm)
Barrel length396 mm (15.6 in)

Cartridge5.56×45mm NATO
ActionGas-operated, rotating bolt
Rate of fireSustained (Short Bursts): 50–60 rounds per minute
Minimum Cyclic: 1225 rds per min
Effective firing range328 yds (300 m)
Feed system30-round STANAG Magazine

The M231 Firing Port Weapon (FPW) is an adapted version of the M16 assault rifle for shooting from firing ports on the M2 Bradley. The M16, standard infantry weapon of the time, was too long for use in a "buttoned up" APC, so the FPW was developed to provide a suitable weapon for this role. Designed by the Rock Island Arsenal, the M231 FPW remains in service. All but the rear two firing ports on the Bradley have been removed.