There were more M1 carbines produced in WW2 than M1 Garands (6.25 million vs 5.5 million) and several variants were introduced. Among them was a modified M2 carbine (which had a 30 rd box mag feeding a carbine that had full-auto capability for emergencies). The next derivitive was the M3 carbine which was a dedicated sniper's rifle with a conical flash hider and a heavy telescopic IR Superscope which became known to troops as a "Snooperscope"! Only 2100 were produced but used to great effect in the PTO against the Japanese who were blind at night. The weapon accounted for 30% of the Japanese killed on Okinawa. Please note that the Germans produced and used more IR in WW2 than all others combined on land, air, and sea! Their formidible rifle was the STG-44 assault rifle fitted with a Vampir ZG-1229 Vampir sight with it own battery pack carried. German Panthers and SdKfz Uhu AFVs worked together to kill enemy tanks at night and in the air several aircraft used Spanner IR to kill RAF Lancs. Also used for Baltic coastal defense batteries and with U-boat periscopes for night hunting!!! They also used Anti-IR devices and developed anti-IR dyes for late Waffen SS combat uniforms!

*M3 was a modified M2 which had emergency full-auto capability and a selector switch fitted. M3 with Superscope fitted: http://www.stardestroyer.net/Armour/ShepStuff/Website/DrakaWB/M3CarbinewithM3.gif