A submachine gun (SMG) is an air-cooled, magazine-fed, automatic carbine designed to fire pistol cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun. Here are the top 10 rarest submachine guns of World War II: 

• #10 - Tsing Tao Arsenal Model 1927 (Nationalist China KMT)
• # 9 - SIG MKMS / MKMO (Switzerland)
• #8 - Suomi KP-26 (Finland)
• #7 - Nambu Type II Model A (Empire Japan)
• #6 - Nambu Type I (Empire Japan)
• #5 - Mukden Arsenal Type II (Manchuria China)
• #4 - Lahti M22 (Finland)
• #3 - Runci Rad I or J. Barbaric M1944 (Croatia)
• #2 - ERMA-Gurt Model 1944 or Gurt M34 (Germany)
• #1 - Kuomintang M1944 (Nationalist China)