A machine pistol is a handgun that is capable of fully automatic fire, including stockless handgun-style submachine guns.
A submachine gun (SMG) is a magazine-fed automatic carbine designed to fire handgun cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an automatic firearm with notably less firepower than a machine gun. As a machine gun must fire rifle cartridges to be classified as such, submachine guns are not considered machine guns. The submachine gun was developed during World War I (1914–1918) as a close quarter offensive weapon, mainly for trench raiding. At its peak during World War II (1939–1945), millions of submachine guns were made for assault troops and auxiliaries whose doctrines emphasized close-quarter suppressive fire. New submachine gun designs appeared frequently during the Cold War, especially among special forces, covert operation commandos and mechanized infantrymen. Submachine gun usage for frontline combat decreased in the 1980s and 1990s, and by the early 21st century, submachine guns have largely been replaced by assault rifles, which have a longer effective range, have increased stopping power, and can better penetrate the helmets and body armor used by modern soldiers. However, they are still used by security forces, police tactical units, paramilitary and bodyguards for close-quarters combat because they are "a pistol-caliber weapon that's easy to control, and less likely to overpenetrate the target".
An automatic firearm or fully automatic firearm is a self-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new ammunition round into the chamber, and then igniting the propellant and discharging the projectile by delivering a hammer or striker impact on the primer.
The MP 18 is a German submachine gun designed and manufactured by Bergmann Waffenfabrik. Introduced into service in 1918 by the German Army during World War I, the MP 18 was intended for use by the Sturmtruppen, assault groups specialized in trench combat, as a short-range offensive weapon that would provide individual soldiers with increased firepower over a pistol.
The Beretta M12 is a 9×19mm Parabellum caliber submachine gun designed by Beretta. Production started in 1959, the first users were the Italian Carabinieri, Italian State Police and the Guardia di Finanza, though in limited numbers; it was only widely issued beginning in 1978, replacing the old Beretta MAB. In 1962 the Italian Army bought a limited number of Franchi LF-57 submachine guns, judged better than the M12 but never issued to the troops, and only in 1992 the M12S2 variant was introduced, in very limited numbers. The Italian Air Force bought instead many M12S and M12S2 for the airport security units. However, the weapon had a higher initial success in the Arab countries and South America.
The Beretta Model 38 was an Italian submachine gun introduced in 1938 and used by the Royal Italian Army during World War II. It was first issued to Italian police units stationed in Italy's African colonies. The Italian army was impressed by the gun's performance and decided to adopt a version to be used by the army's elite formations and military police, but requested a modified variant which had no bayonet and a different muzzle brake. This variant was widely used by the Royal Italian Army on all theatres of World War II Italy was involved in. The guns were also used by the German, Romanian and Argentine militaries of the era.
The Beretta Cx4 Storm is a pistol-calibre semi-automatic carbine aimed at the sporting, personal defense and law enforcement markets. It was designed to accept magazines from different Beretta pistol platforms using adapters. The CX4 is available in 9×19mm Parabellum, .40 S&W, .45 ACP, and 9×21mm models. The .45 model can only use 8000 "Cougar" magazines.
The Pistola Mitragliatrice Fiat Mod. 1915, commonly nicknamed the Villar Perosa, was an Italian portable automatic weapon developed during World War I by the Officine di Villar Perosa.
The Frommer Stop is a Hungarian semi-automatic pistol which was manufactured by small arms firm Fegyver- és Gépgyár (FÉG) in Budapest. It was designed by Rudolf Frommer and adopted by the Austro-Hungarian Army in 1912 as the Pisztoly 12M. The pistol was manufactured in various forms from 1912 to 1945 and was also used by the Ottoman Army and the Royal Hungarian Army, seeing action in World War I and World War II. Its design features a 165 millimeters (6.5 in) long with a 95 millimeters (3.7 in) 4-groove rifled barrel. Unloaded weight is 610 g (22 oz), and the detachable box magazine holds seven rounds.
The Carabinetta Automatica O.V.P was a submachine gun developed in Italy.
The Glisenti Model 1910 was a 9 mm calibre semi-automatic service pistol produced by the Italian company Società Siderurgica Glisenti. It was put in production in 1910 to replace the aging Bodeo Model 1889. It saw extensive service in World War I and World War II with the Royal Italian Army. The Model 1910 has a complex and weak firing system which mandates that the pistol ought to use weaker cartridges than pistols of comparable calibre.
The 9mm Glisenti is an Italian pistol and submachine gun cartridge.
The Beretta Model 1923 pistol was a service pistol used by the Italian Army from 1923 until 1945. The M1923 was designed to consolidate the improvements of the 1915/19 model and to use the 9mm Glisenti round. However, due to the vast amount of handguns available after the end of World War I only 3000 samples, of about 10.000 produced, were purchased by the Italian Army.
The Beretta Model 1915 or Beretta M1915 is a semi-automatic pistol manufactured by Beretta, designed by Tullio Marengoni who was the chief engineer in the company, to replace the Glisenti Model 1910 which had a complex and weak firing mechanism. It is the first semi-automatic pistol, manufactured by the company, and issued as a service pistol in Royal Italian Army during World War I. The total production of the Beretta M1915 is estimated about 15,600 during 1915-1918, and about 56,000 of Beretta M1915/1917. Some of the pistols were also used in World War II until 1945. Its open slide design later became the characteristic for other Beretta pistols such as Beretta M1923, Beretta M1934, Beretta M1935, Beretta M1951, Beretta 70, Beretta 92, Beretta Cheetah, and Beretta M9.
Italy 
Albania [ citation needed ]
Argentina :Beretta 1918/30 in 9mm Parabellum [5] adopted in 1933 by the Federal Police, [5] and Buenos Aires Provincial Police
Ethiopia Surplus mod.1915 and mod.1918/30 were bought from Italy and issued to the Kebur Zabagna, [7] [5] possibly some were also shipped to Eritrea and captured by the Ethiopians [1] 
Saudi Arabia :Purchased surplus Carbines, [7] possibly around 1938 [4] 
La Cagoule:A number of Mod.1918/30 carbines were smuggled by OVRA in exchange for favours to the Italian government. [1] 
