Question: Who invented Machine Gun Kelly's favorite weapon?

Context paragraphs:
Till I Die (Machine Gun Kelly song): "Till I Die" is a song by American rapper Machine Gun Kelly.  The song premiered via YouTube, on January 5, 2015 and was released in the US on January 6, as the lead single from Machine Gun Kelly's sophomore studio album, "General Admission".  It contains references to artists from Cleveland, as well as to the life in the state of Ohio.  The song received positive reviews, with critics praising MGK's lyrical ability and inert references to Cleveland, describing the song as a "perfect trap anthem".  The song was produced by J.U.S.T.I.C.E. League when the song was recorded in 2014, and the group also handled the distribution of the song.  A new version of the song is also featured on the soundtrack for "NBA 2K16".

Machine Gun Kelly: George Kelly Barnes (July 18, 1895 – July 18, 1954), better known as "Machine Gun Kelly", was an American gangster from Memphis, Tennessee, during the prohibition era.  He attended Central High School in Memphis.  His nickname came from his favorite weapon, a Thompson submachine gun.  His most infamous crime was the kidnapping of oil tycoon and businessman Charles F. Urschel in July 1933 for which he, and his gang, collected a $200,000 ransom.  Their victim had collected and left considerable evidence that assisted the subsequent FBI investigation that eventually led to Kelly's arrest in Memphis, Tennessee, on September 26, 1933.  His crimes also included bootlegging and armed robbery.

M249 light machine gun: The M249 light machine gun (LMG), formerly designated the M249 Squad Automatic Weapon (SAW) and formally written as Light Machine Gun, 5.56 mm, M249, is the American adaptation of the Belgian FN Minimi, a light machine gun manufactured by the Belgian company FN Herstal (FN).  The M249 is manufactured in the United States by the local subsidiary FN Manufacturing LLC in South Carolina and is widely used in the U.S. Armed Forces.  The weapon was introduced in 1984 after being judged the most effective of a number of candidate weapons to address the lack of automatic firepower in small units.  The M249 provides infantry squads with the high rate of fire of a machine gun combined with accuracy and portability approaching that of a rifle.

Degtyaryov machine gun: The Degtyaryov machine gun (Russian: Пулемёт Дегтярёвa Пехотный "Pulemyot Degtyaryova Pekhotny" "Degtyaryov's infantry machine gun") or DP-28 is a light machine gun firing the 7.62×54mmR cartridge that was used primarily by the Soviet Union starting in 1928.  The DP machine gun was supplemented in the 1950s by the more modern RPD machine gun and entirely replaced in Soviet service by the general purpose PK machine gun in the 1960s.

Bailey machine gun: The Bailey Machine Gun was a rapid-fire weapon developed in the late 19th century.  It was a multiple barrel weapon similar to the much more commonly known Gatling gun, and was the first weapon of this type to be belt-fed.  Although commonly referred to as the Bailey Machine Gun, it is technically not a machine gun since it is externally powered using a hand crank.  However, rapid-fire weapons of this type are commonly referred to as machine guns, even though this usage of the term is technically incorrect.

St. Étienne Mle 1907: The French St. Étienne Mle 1907 (French: "Mitrailleuse Mle 1907 T" ) was a gas operated air-cooled machine gun in 8mm Lebel which was widely used in the early years of the First World War.  The "St.Etienne Mle 1907" was not derived from the Hotchkiss machine gun.  Instead it was an entirely different gas operated blow-forward design borrowed from the semi-automatic Bang rifle of 1903.  This Bang system was first transposed in 1905 to the French Puteaux APX Machine Gun which soon proved to be unsatisfactory.  Then, two years later, the Mle 1907 "St-Etienne" machine gun followed as an improved redesign of the "Puteaux" machine gun.  However the Mle 1907 "Saint Etienne" was only a partial redesign : the original blow-forward gas piston, rack-and-pinion system, and bolt mechanism of the Mle 1905 " Puteaux" machine gun had all been kept only slightly modified inside the newer weapon.  Eventually a total of over 39,700 "St-Etienne" Mle 1907 machine guns were manufactured between 1908 and late 1917.  They were widely used by French infantry during the early part of World War I until their replacement by the distinctly more reliable Hotchkiss M1914 machine-gun.

At My Best: "At My Best" is a song by American rapper Machine Gun Kelly, featuring American singer Hailee Steinfeld.  It was released on March 17, 2017 via Bad Boy and Interscope.  It is Machine Gun Kelly's second single to enter "Billboard" Hot 100 after his 2016 collaboration with Camila Cabello, "Bad Things".

Thompson 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".

Kk 62: The Kk 62 , also known as Kvkk 62 (konekivääri 62 "machine gun 62" or kevyt konekivääri 62 "light machine gun 62") is a Finnish 7.62×39mm light machine gun designed in late 1950s with the first prototype ready for testing in 1960.  It was officially adopted as the standard infantry support weapon of the Finnish Defence Forces (FDF) in 1962 as the 7.62 "konekivääri" 62; the first weapons were delivered in 1966.  It remains in service, although a replacement has already entered use, namely the PKM general-purpose machine gun.  The weapon is known for its unreliability and is highly unpopular among Finnish conscripts.

M2 Browning: The M2 Machine Gun or Browning .50 Caliber Machine Gun is a heavy machine gun designed toward the end of World War I by John Browning.  Its design is similar to Browning's earlier M1919 Browning machine gun, which was chambered for the .30-06 cartridge.  The M2 uses the much larger and much more powerful .50 BMG cartridge, which was developed alongside and takes its name from the gun itself (BMG standing for "Browning Machine Gun").  It has been referred to as "Ma Deuce", in reference to its M2 nomenclature.  The design has had many specific designations; the official designation for the current infantry type is Browning Machine Gun, Cal.  .50, M2, HB, Flexible.  It is effective against infantry, unarmored or lightly armored vehicles and boats, light fortifications and low-flying aircraft.  The M2 has been produced longer than any other machine gun.

Supporting paragraphs: Machine Gun Kelly Thompson submachine gun
Answer: John T. Thompson