One of the driving forces in the design of the M2/M3 Bradley family of vehicles was the desire to match the Soviet BMP-1 in capability. The Army had nothing like the BMP. The BMP carried infantry soldiers to the battlefield, it had a built in Anti-Tank Guided Missile (ATGM) and a main gun that could defeat armored personnel carriers. One feature that would influence the Bradley was the ability to “fight mounted.”
This photo of a model of a BMP shows the firing ports on the side of the vehicle. Infantrymen (or, in the Soviet Army, motorized riflemen) could fire their AKM rifles through these ports, aiming them by means of the vision blocks mounted above. The chances of hitting anything were slim, but the idea was to suppress enemy infantry and anti-armor teams while sweeping through their positions. This ability to fight while under armor caught the imagination of US Army planners. While the M-113 ACAV modification was used to fight mounted in Vietnam, casualties were high among gunners, even after gun shields were installed.
During the long development of the Bradley, designers went to great lengths to make it possible for the infantrymen inside to provide suppressive fires. The seating arrangement in the rear was designed so the infantrymen would be facing the outside of the vehicle.
Instead of the simple bench seats of the M-113, this required each dismount to have his own seat, one that could be folded and moved so the team could quickly dismount when the ramp came down.
The next issue became the weapon. The standard M-16 was just too long to place in a firing port. What for the Soviets was a simple hole in the side of the track, became for the US a new weapon system. Rock Island arsenal modified the M-16 design to produce a new weapon that could be used. This involved shortening the weapon and removing the front (and eventually rear) sight. The rear stock was removed. The front handguard was replaced and the barrel was shortened. Most importantly, the weapon was converted to fire full automatic only and the rate of fire was increased to 1200 rounds per minute. This was the M231. Since the firing port weapon (FPW) would be aimed by looking out of the vision blocks above it, the weapon fired tracers only. The firer would “walk” the tracers onto the target. Several spare 30 round magazines for these weapons were stored under each seat, a separate supply of ammunition from their own personal weapons.
These weapons screw into a ball-joint in the side of the vehicle. There were two ports on each side and two ports on the rear ramp for a total of six weapons. The ball joints were air-tight. To prevent a build up of dangerous gun gases in the compartment, each weapon had a brass catcher bag with a hose attached to a fan to vent the gases.
All in all, the Army had put a lot of time, money and effort into making sure the Bradley had 360° coverage for short range suppressive fires while mounted under armor. There was just one problem. It didn’t work worth a damn. The vision blocks were extremely difficult to look out of, much less use to aim a weapon. When the Bradley was moving, the vibration of the vehicle made vision almost impossible. The high rate of fire combined with the 30 round magazine meant that by the time you managed to walk the tracers to the target, you were out of ammo and had to reload. Also, because of the limited space inside the Bradley, most of the teams personal equipment had to be stored by strapping it to the outside of the vehicle. This blocked the arcs of fire for the weapons. The rear ramp could not be lowered with the FPWs in place. They had to be unscrewed and stored before the team could dismount. Finally, and most importantly, the Army realized that any terrain that was close enough to require suppressive small arms fires would need to be cleared by dismount infantry anyway, negating the whole concept.
The M2A1 maintained all six firing ports, but the M2A2 deleted the firing ports on the side in favor of heavier applique armor. This left only the two firing ports in the rear ramp. After Desert Storm, the complex individual seating arrangement was deleted in favor of a simple bench seating arrangement much like the M-113. This made mounting and dismounting much simpler and quicker.* While the capability to use FPWs in the ramp remains, this is rarely done.
I’ve only used the FPWs once. While I was a dismounted team leader in Colorado, we did a live-fire assault course. The first run through had us dismounting and making a conventional assault by fire and movement with supporting fire from the Bradley. The next iteration had us making a mounted assault using the FPWs. I managed to get off 2 magazines, but I never even saw the targets. I’m fairly certain no one else did either. Afterwards, rather than turning in the surplus ammo, we took the FPWs out of the vehicle and fired them like submachine guns. Since there are no sights and no stock, it is an extraordinarily inaccurate weapon. I suppose you could hit a targe at 50 meters, but even that would be a stretch.
Interestingly, FPWs are still in service. While looking for a picture of an FPW, I came across this photo of then PFC Ross McGinnis in the turret of an up-armored Humvee.
In addition to his M-2 .50cal machine gun and M-4 carbine, he has an M-231 FPW for close in work. This photo of McGinnis ran in Stars and Stripes a few days before the action in which he lost his life and earned the Medal of Honor.
*As an added bonus, when the dismounts are off the vehicle, the bench seats make excellent cots for the Bradley Commander or Gunner to sleep on. The Driver almost universally sleeps in his compartment.