Infrared sight versions The M3 carbine was an M2 carbine with the M2 infrared night sight or sniperscope. The M3 did not have iron sights. It was first used in combat by Army units during the invasion of Okinawa, where about 150 M3 carbines were used. For the first time, U.S. soldiers had a weapon that allowed them to visually detect Japanese infiltrating into American lines at night, even during complete darkness. A team of two or three soldiers was used to operate the weapon and provide support. At night, the scope would be used to detect Japanese patrols and assault units moving forward. At that point, the operator would fire a burst of automatic fire at the greenish images of enemy soldiers. The M3 carbine had an effective range of about 70 yards (64 meters), limited by the visual capabilities of the sight. Fog and rain further reduced the weapon's effective range. However, it is estimated that 30% of Japanese casualties inflicted by rifle and carbine fire during the Okinawan campaign were caused by the M3 carbine.
Infrared sight versions The M3 carbine was an M2 carbine with the M2 infrared night sight or sniperscope. The M3 did not have iron sights. It was first used in combat by Army units during the invasion of Okinawa, where about 150 M3 carbines were used. For the first time, U.S. soldiers had a weapon that allowed them to visually detect Japanese infiltrating into American lines at night, even during complete darkness. A team of two or three soldiers was used to operate the weapon and provide support. At night, the scope would be used to detect Japanese patrols and assault units moving forward. At that point, the operator would fire a burst of automatic fire at the greenish images of enemy soldiers. The M3 carbine had an effective range of about 70 yards (64 meters), limited by the visual capabilities of the sight. Fog and rain further reduced the weapon's effective range. However, it is estimated that 30% of Japanese casualties inflicted by rifle and carbine fire during the Okinawan campaign were caused by the M3 carbine.