Question: When was the gun invented that chambered the same .45 round as the M3 submachine gun?
Context: The M56 submachine gun is a Yugoslavian submachine gun chambered in 7.62×25mm Tokarev, designed for use with the Yugoslav People's Army.  Initially a state-funded product, it was later produced by Zastava Arms and saw use in a number of conflicts following the breakup of former Yugoslavia.  The M56 is a clone of the MP 40 submachine gun used by Nazi Germany, easily distinguished from the MP 40 by its increased length and curved magazine. The Daewoo Precision Industries K1/K1A is a South Korean carbine assault rifle, the first modern firearm developed by Agency for Defense Development (ADD) and manufactured by Daewoo Precision Industries, and entered service in the Republic of Korea Armed Forces in 1981.  Although the K1 uses .223 Remington, it is classified as a submachine gun by the South Korean military and the current manufacturer S&T Motiv, because the K1 was intended to replace the M3 submachine gun. The Thompson submachine gun is an American submachine gun, invented by John T. Thompson in 1918, that became infamous during the Prohibition era.  It was a common sight in the media of the time, being used by both law enforcement officers and criminals.  The Thompson submachine gun was also known informally as the "Tommy Gun", "Annihilator", "Chicago Typewriter", "Chicago Piano", "Chicago Style", "Chicago Organ Grinder", "Trench Broom", "Trench Sweeper", "The Chopper", and simply "The Thompson". The New Nambu M65/M66 is a submachine gun of post-World War II Japanese origin manufactured by Shin-Chuō Industries (Formerly Nambu Arms Manufacturing Company; now Minebea).  It is a blowback, open-bolt configured weapon chambered in the 9×19mm Parabellum round fed from a thirty-round magazine.  The firearm was only tested and produced under trials for the considered replacement of the aging M3 submachine gun that was supplied by the United States Military during the formation of the National Police Reserve after the war. MCEM-2 (Machine Carbine Experimental Model 2) submachine gun was produced only in prototype form, but was one of the very first submachine guns to combine wrap-around bolt and magazine in pistol grip, features later copied in the Czechoslovak Sa vz.  23, Israeli Uzi and a great number of other submachine guns.  MCEM-2 was the second prototype in a line of experimental submachine guns, designed in Britain in 1944.  It was envisioned as a possible replacement for the STEN submachine gun then in service.  The MCEM-2 was developed by Jerzy Podsedkowski, a Polish constructor involved in work on Vis and Mors, who fled from occupied Poland to Britain.  It is believed that prototypes of MCEM-2 were made before the end of WW2, and its derivatives MCEM-4 and MCEM-6 were tested soon after the war.  The latter modifications differed mostly in adoption of the rate-reducing mechanism, incorporated into trigger unit; the rate of fire therefore was decreased from 1000 to more realistic 600 rounds per minute.  Nevertheless, neither prototype was found suitable for adoption, and several years later British army adopted a more conventional submachine gun, the Sterling-Patchett. The Beretta Model 1918 was a submachine gun that entered service in 1918 with the Italian armed forces.  Designed initially as a semi-automatic rifle, the weapon came with an overhead inserted magazine, an unconventional design based on the simplicity of allowing a spent round to be replaced using only gravity.  The gun was made from half of a Villar-Perosa aircraft submachine gun, and as such it can be considered the first submachine gun issued to and used by the Italian armed forces, and is possibly the first SMG used as a general-issue combat weapon. The M3 was an American .45-caliber submachine gun adopted for U.S. Army service on 12 December 1942, as the United States Submachine Gun, Cal.  .45, M3.  The M3 was chambered for the same .45 round fired by the Thompson submachine gun, but was cheaper to produce, and lighter, although, contrary to popular belief, it was far less accurate.  This myth stems from a US army training film portraying the M3 as more accurate than its counterparts.  The M3 was commonly referred to as the "Grease Gun" or simply "the Greaser," owing to its visual similarity to the mechanic's tool. The Hyde-Inland M2 was a United States submachine gun design submitted for trials at Aberdeen Proving Ground in February, 1941.  Work was undertaken by General Motors Inland Manufacturing Division to develop workable prototypes of George Hyde's design patented in 1935.  The model first submitted for trials in April 1942 was designated the "Hyde-Inland 1".  Trials revealed the design was superior to the M1 submachine gun in mud and dirt tests, and its accuracy in full-automatic firing was better than any other submachine gun tested at the time.  An improved "Hyde-Inland 2" was designated U.S. Submachine gun, Caliber .45, M2 as a substitute standard for the M1 Thompson in April, 1942.  As Inland's manufacturing capacity became focused on M1 carbine production, the US Army contracted M2 production to Marlin Firearms in July, 1942.  Marlin began production in May 1943.  Marlin's production failed to match the trials prototype performance; and Marlin's original contract for 164,450 M2s was canceled in 1943 upon adoption of the M3 submachine gun.  The M2 is chambered for the .45 ACP cartridge and used the same 20- or 30-round magazine as the Thompson.  Its cyclic rate of fire is 570 rounds per minute.  None of the approximately 400 manufactured were issued by any branches of the United States military. The Arsenal M23 submachine gun (Estonian: "Arsenali püstolkuulipilduja" ) (also known as Arsenal Tallinn) was an Estonian submachine gun from 1926 through 1935.  These submachine guns were designed and produced in the Estonian military equipment factory "Arsenal" in Karjamaa, Tallinn, but production was not more than 600 units.  The weapon was chambered for the 9x20 mm semi-rimmed Browning cartridge to be compatible with ammunition for the Browning FN M1903 pistol which had been adopted by the Estonian Army.  It operated on the blowback system and was essentially similar to the MP18.1; having a wooden stock, slotted barrel jacket, and horizontal left side magazine feed.  A uniquely slender 40 round single column box magazine led to frequent cartridge feeding problems; and cooling fins which were machined lengthwise along the barrel to promote cooling air flow when firing (similar to the Lewis machine gun), unnecessarily complicated production.  It was used by the combat support units of the Border Guard, the Estonian Defence League and the Estonian Defence Forces.  The Arsenal submachine gun was replaced in Estonian service by the Finnish Suomi KP/-31 submachine gun in 1938.  The Estonian Army sold a few samples to Latvia and all of the remainder found their way to Republican forces during the Civil War in Spain. The Type 64 submachine gun is a submachine gun of Chinese origin.  Designed for silent operation, the Type 64 has an integral suppressor making the weapon considerably quieter.  The weapon is a magazine-fed selective-fire submachine gun using a closed-bolt, blowback action, chambered for 7.62×25mm Type 51 (A Chinese manufactured version of the 7.62×25mm Tokarev round).
Answer: 1918