Question: The Northrop P-61 Black Widow had a gun mounted that was designed by whom?

Context paragraphs:
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.

Northrop P-61 Black Widow: The Northrop P-61 Black Widow, named for the American spider, was the first operational U.S. warplane designed as a night fighter, and the first aircraft designed to use radar.  The P-61 had a crew of three: pilot, gunner, and radar operator.  It was armed with four 20 mm (.79 in) Hispano M2 forward-firing cannons mounted in the lower fuselage, and four .50 in (12.7 mm) M2 Browning machine guns mounted in a remote-controlled dorsal gun turret.

Black Widow (Black Widow album): Black Widow is the eponymous second album by English rock band Black Widow.  It was issued in 1971 on CBS Records (the same year Black Sabbath's "Master of Reality" was released) and was produced by Patrick Meehan Jr. On "Black Widow", the occult-based lyrical themes that had dominated the band's debut disappeared.

James Puckle: James Puckle (1667–1724) was an English inventor, lawyer and writer from London chiefly remembered for his invention of the "Defence Gun", better known as the "Puckle gun", a multi-shot gun mounted on a stand capable of (depending on which version) firing up to nine rounds per minute.  The Puckle gun is one of the first weapons referred to as a machine gun (though its operation does not match the modern definition of the term) and resembles a large revolver.

AK-176: The AK-176 is a Soviet naval gun mounted in an enclosed turret, that may be used against sea, coastal, and aerial targets, including low flying anti-ship missiles.  The system is designed to arm small displacement ships and comprises the Gun Mount with a MR-123-02/76 Fire Control Radar System.  It has high survivability owing to autonomous use of the gun mount controlled from the optical sight in the absence of control from the radar system, as well as a capability for fire, if power supply is lost.

14&quot;/50 caliber gun: The 14"/50 caliber gun was a naval gun mounted on "New Mexico" and "Tennessee"-class battleship s.  These ships also featured the first "three-gun" turrets, meaning that each gun in each turret could be "individually sleeved" to elevate separately (however, they could be linked so they would elevate as a unit, similar to the triple turrets on other Navy ships).  The 14"/50 caliber guns were designated as Mark 4 and 6, with later versions known as Mark 7, 11, and B.  These guns were more powerful than the main gun mounted on the previous three classes of US battleships (the "New York" , "Nevada" and "Pennsylvania" class es), the 14"/45 caliber gun. <ref name="14/50"> </ref>

Latrodectus variolus: Latrodectus variolus, the northern black widow spider or northern widow, is a medically important spider species of the genus "Latrodectus" in the family Theridiidae.  The population is closely related to the southern black widow, "Latrodectus mactans", and the western black widow, "Latrodectus hesperus", of the genus.

Curtiss-Wright XF-87 Blackhawk: The Curtiss-Wright XF-87 Blackhawk (previously designated the XP-87) was a prototype American all-weather jet fighter interceptor and the company's last aircraft project.  Designed as a replacement for the World War II–era propeller-driven P-61 Black Widow night/interceptor aircraft, the XF-87 lost in government procurement competition to the Northrop F-89 Scorpion.  The loss of the contract was fatal to the company; the Curtiss-Wright Corporation closed down its aviation division, selling its assets to North American Aviation.

Disappearing gun: A disappearing gun, a gun mounted on a "disappearing carriage", is an obsolete type of artillery which enabled a gun to hide from direct fire and observation.  The overwhelming majority of carriage designs enabled the gun to rotate backwards and down behind a parapet, or into a pit protected by a wall after it was fired; a small number were simply barbette mounts on a retractable platform.  Either way, retraction lowered the gun from view and direct fire by the enemy while it was being reloaded.

Northrop F-15 Reporter: The Northrop F-15 Reporter (later RF-61) was an American unarmed photographic reconnaissance aircraft.  Based on the Northrop P-61 Black Widow night fighter, it was the last piston-powered photo-reconnaissance aircraft designed and produced for the United States Air Force.  Though produced in limited quantities, and with a relatively short service life, the F-15's aerial photographs of the Korean Peninsula would prove vital in 1950, when North Korea invaded the south.

Supporting paragraphs: Northrop P-61 Black Widow M2 Browning
Answer: John Browning