Question: What gun did the machine gun that the MG 3 is derived from replace?

Context paragraphs:
MG 17 machine gun: The MG 17 was a 7.92 mm machine gun produced by Rheinmetall-Borsig for use at fixed mountings in many World War II Luftwaffe aircraft, typically as forward-firing offensive armament, but also used as fixed, remotely-fired tail guns in certain aircraft variants, such as the Do 217.  The MG 17 was based on the older MG 30 light machine gun, as was its defensive flexible-mount counterpart, the MG 15 machine gun, which was of the same caliber and general size.  Modifications to the design included removal of the buttstock, switching from magazine to belt-fed ammunition, and from open-bolt operation to closed bolt operation, to allow it to be installed in synchronized applications, firing through the propeller arc.  The MG 15 retained open bolt operation, but used 75 round saddle-type drum magazines, and likewise lost its buttstock, to fit better in the tight confines of an aircraft.  The MG 30 was also the basis for the famed MG 34 and MG 42 designs; variants of the latter are still in service in certain areas.

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.

MG 42: The MG 42 (shortened from German: "Maschinengewehr 42", or "machine gun 42") is a 7.92×57mm Mauser general purpose machine gun designed in Nazi Germany and used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II.  It was intended to replace the earlier MG 34, which was more expensive and took much longer to produce, but both weapons were produced until the end of the war.

Type 1 machine gun: The Type 1 machine gun was developed for aerial use for the Imperial Japanese Army and Navy during World War II.  It was an adaptation of the German MG 15 machine gun.  (Note that the 12.7mm Ho-103 and H-104 machine guns are also known as the "Type 1 machine gun", but are actually a 12.7mm adaption of the Browning M1919 machine gun in fixed and flexible mountings, respectively.)

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.

MG 29: The Flieger MG 29 (also called the Flab MG or FLab MG 29/38) was a Swiss light machine gun developed in the 1920s and produced until shortly before the dawn of the Second World War.  It was mounted on aircraft and was later used as an anti-aircraft gun.  However, it was too heavy to be used as am infantry support weapon.  It employed a closed bolt system.  Some guns had the ability to bolt a large box onto the bottom of the machine gun to hold the ammunition belt.  Two versions of the gun existed, the "normal" version and a second version which bolted two guns together and made them to fire from the same trigger, known as the "Doppel-MG" (double machine gun).  After the second world war, better anti aircraft systems and aircraft weapons were available to Switzerland and the infantry support role was filled by the MG 51.  The higher rate of fire, but much heavier MG 29 was finally mounted on the first prototype of the Panzer 58, the precursor to the more famous Panzer 61 tank before being retired.

Rheinmetall MG 3: The MG 3 is a German general-purpose machine gun chambered for the 7.62×51mm NATO cartridge.  The weapon's design is derived from the World War II era MG 42 universal machine gun that fired the 7.92×57mm Mauser round.

MG 51: The 7.5 mm Maschinengewehr 1951 or Mg 51 is a general-purpose machine gun manufactured by W+F of Switzerland.  The weapon was introduced into Swiss service when the Swiss Army initiated a competition for a new service machine gun to replace the MG 11 heavy machine gun and the Furrer M25 light machine gun adopted in 1911 and 1925 respectively.

Canadian Machine Gun Corps: The Canadian Machine Gun Corps (CMGC) was an administrative corps of the Canadian Army.  It was part of the Canadian Expeditionary Force sent to France during World War I.  The Canadian Permanent Machine Gun Brigade was organized in the Permanent Force on 3 November 1919.  The Canadian Permanent Machine Gun Brigade was redesignated the Royal Canadian Permanent Machine Gun Brigade on 16 June 1921.  The Royal Canadian Permanent Machine Gun Brigade was disbanded on 1 November 1923.  The Canadian Machine Gun Corps donated a wall plaque at St. George's Church in Ypres.

MG 3: The MG 3 is a budget supermini car produced by the Chinese automotive giant SAIC.  The first generation, marketed as the MG 3 SW, is based on the British made Rover Streetwise, which itself was based on the Rover 25, while the second generation, introduced in 2011 is marketed simply as the MG 3.  It is the most popular Chinese manufactured car currently on sale in the United Kingdom.

Supporting paragraphs: Rheinmetall MG 3 MG 42
Answer: MG 34