M2 with mounting (T3 mount) for an early active (infrared) night vision sight
About 3,000 produced
Three versions of night sight (M1, M2, M3)
The M3 carbine was an M2 carbine fitted with a mount designed to accept an infrared sight for use at night.
 It was initially used with the M1 sniperscope, and an active infrared sight, and saw action in 1945 with the Army during the invasion of Okinawa.
 Before the M3 carbine and M1 sniperscope were type-classified, they were known as the T3 and T120, respectively.
The system continued to be developed, and by the time of the Korean War, the M3 carbine was used with the M3 sniperscope.

The M2 sniper scope extended the effective nighttime range of the M3 carbine to 100 yards.
 In the later stages of the Korean War, an improved version of the M3 carbine, with a revised mount, a forward pistol grip, and a new M3 sniperscope design was used in the latter stages of Korea and briefly in Vietnam.
 The M3 sniperscope had a large active infrared spotlight mounted on top of the scope body itself, allowing use in the prone position.
The revised M3/M3 had an effective range of around 125 yards.
Eventually, the M3 carbine and its M3 sniperscope would be superseded by passive-design night vision scopes with extended visible ranges; the improved scopes in turn required the use of rifle-caliber weapons with flatter trajectories and increased hit probability.
M2 with mounting (T3 mount) for an early active (infrared) night vision sight
About 3,000 produced
Three versions of night sight (M1, M2, M3)
The M3 carbine was an M2 carbine fitted with a mount designed to accept an infrared sight for use at night.  It was initially used with the M1 sniperscope, and an active infrared sight, and saw action in 1945 with the Army during the invasion of Okinawa.  Before the M3 carbine and M1 sniperscope were type-classified, they were known as the T3 and T120, respectively. The system continued to be developed, and by the time of the Korean War, the M3 carbine was used with the M3 sniperscope.
The M2 sniper scope extended the effective nighttime range of the M3 carbine to 100 yards.  In the later stages of the Korean War, an improved version of the M3 carbine, with a revised mount, a forward pistol grip, and a new M3 sniperscope design was used in the latter stages of Korea and briefly in Vietnam.  The M3 sniperscope had a large active infrared spotlight mounted on top of the scope body itself, allowing use in the prone position. The revised M3/M3 had an effective range of around 125 yards. Eventually, the M3 carbine and its M3 sniperscope would be superseded by passive-design night vision scopes with extended visible ranges; the improved scopes in turn required the use of rifle-caliber weapons with flatter trajectories and increased hit probability.
M1 carbine