John Browning had the idea for this round during World War I in response to a need for an anti-aircraft weapon, based on a scaled-up .30-06 Springfield design, used in a machine gun based on a scaled-up M1919/M1917 design that Browning had initially developed around 1900 (but which was not adopted by the U.S. military until 1917, hence the model designation).
Armor-piercing incendiary tracer (APIT) rounds were especially effective against aircraft, and the AP rounds and armor-piercing incendiary (API) rounds were excellent for destroying concrete bunkers, structures, and lighter armored fighting vehicles (AFVs).
The API and APIT rounds left a flash, report, and smoke on contact, useful in detecting strikes on targets.

The development of the .50 BMG round is sometimes confused with the German 13.2 mm TuF, which was developed by Germany for an anti-tank rifle to combat British tanks during WWI and against aircraft.
 According to the American Rifleman: "Actually, the Browning .50 originated in the Great War.
American interest in an armor-piercing cartridge was influenced by the marginal French 11 mm design, prompting U.S. Army Ordnance officers to consult Browning.
They wanted a heavy projectile at 2700 feet per second (f.p.s.),
but the ammunition did not exist.
Browning pondered the situation and, according to his son John, replied, 'Well, the cartridge sounds pretty good to start.
You make up some cartridges and we'll do some shooting.'"

The American Rifleman further explains that development was "[r]eputedly influenced by Germany's 13.2x92 mm SR (.53-cal.)
anti-tank rifle" and that then "Ordnance contracted with Winchester to design a .50-cal.
cartridge.
Subsequently, Frankford Arsenal took over from Winchester, producing the historic .50 BMG or 12.7x99 mm cartridge.
The Army then returned to John Browning for the actual gun.
Teamed with Colt, he produced prototypes ready for testing and, ironically, completed them by Nov. 11, 1918—the Great War's end."

The round was put into use in the M1921 Browning machine gun.
This gun was later developed into the M2HB Browning which with its .50 caliber armor-piercing cartridges went on to function as an anti-aircraft and anti-vehicular machine gun, capable of penetrating 0.9 inches (23 mm) of face-hardened armor steel plate at 200 meters (220 yd), 1 inch (25 mm) of rolled homogeneous armor at the same range, and 0.75 inches (19 mm) at 547 yards (500 m).

The concept of a .50 caliber machine gun was not an invention of this era; this caliber (.50 inch) had been used in Maxim machine guns and in a number of manual rapid-fire guns such as the original Gatling gun, although these were much lower power cartridges.

During World War II the .50 BMG was primarily used in the M2 Browning machine gun, in both its "light barrel" aircraft mount version and the "heavy barrel" (HB) version on ground vehicles, for anti-aircraft purposes.
An upgraded variant of the M2 Browning HB machine gun used during World War II is still in use today.
Since the mid-1950s, some armored personnel carriers and utility vehicles have been made to withstand 12.7 mm machine gun fire, restricting the destructive capability of the M2.
It still has more penetrating power than lighter weapons such as general-purpose machine guns, though it is significantly heavier and more cumbersome to transport.
Its range and accuracy, however, are superior to light machine guns when fixed on tripods, and it has not been replaced as the standard caliber for Western vehicle-mounted machine guns (Soviet and CIS armored vehicles mount 12.7×108mm NSVs, which are ballistically similar to .50 BMGs).

Decades later, the .50 BMG was chambered in high-powered rifles as well.
The Barrett M82 .50 caliber rifle and later variants were developed during the 1980s and have upgraded the anti-materiel power of the military sniper.
A skilled sniper can effectively neutralize an infantry unit by eliminating several targets (soldiers or equipment) without revealing his precise location.
The long range (over one mile) between firing position and target allows
John Browning had the idea for this round during World War I in response to a need for an anti-aircraft weapon, based on a scaled-up .30-06 Springfield design, used in a machine gun based on a scaled-up M1919/M1917 design that Browning had initially developed around 1900 (but which was not adopted by the U.S. military until 1917, hence the model designation). Armor-piercing incendiary tracer (APIT) rounds were especially effective against aircraft, and the AP rounds and armor-piercing incendiary (API) rounds were excellent for destroying concrete bunkers, structures, and lighter armored fighting vehicles (AFVs). The API and APIT rounds left a flash, report, and smoke on contact, useful in detecting strikes on targets.
The development of the .50 BMG round is sometimes confused with the German 13.2 mm TuF, which was developed by Germany for an anti-tank rifle to combat British tanks during WWI and against aircraft.  According to the American Rifleman: "Actually, the Browning .50 originated in the Great War. American interest in an armor-piercing cartridge was influenced by the marginal French 11 mm design, prompting U.S. Army Ordnance officers to consult Browning. They wanted a heavy projectile at 2700 feet per second (f.p.s.), but the ammunition did not exist. Browning pondered the situation and, according to his son John, replied, 'Well, the cartridge sounds pretty good to start. You make up some cartridges and we'll do some shooting.'"
The American Rifleman further explains that development was "[r]eputedly influenced by Germany's 13.2x92 mm SR (.53-cal.) anti-tank rifle" and that then "Ordnance contracted with Winchester to design a .50-cal. cartridge. Subsequently, Frankford Arsenal took over from Winchester, producing the historic .50 BMG or 12.7x99 mm cartridge. The Army then returned to John Browning for the actual gun. Teamed with Colt, he produced prototypes ready for testing and, ironically, completed them by Nov. 11, 1918—the Great War's end."
The round was put into use in the M1921 Browning machine gun. This gun was later developed into the M2HB Browning which with its .50 caliber armor-piercing cartridges went on to function as an anti-aircraft and anti-vehicular machine gun, capable of penetrating 0.9 inches (23 mm) of face-hardened armor steel plate at 200 meters (220 yd), 1 inch (25 mm) of rolled homogeneous armor at the same range, and 0.75 inches (19 mm) at 547 yards (500 m).
The concept of a .50 caliber machine gun was not an invention of this era; this caliber (.50 inch) had been used in Maxim machine guns and in a number of manual rapid-fire guns such as the original Gatling gun, although these were much lower power cartridges.
During World War II the .50 BMG was primarily used in the M2 Browning machine gun, in both its "light barrel" aircraft mount version and the "heavy barrel" (HB) version on ground vehicles, for anti-aircraft purposes. An upgraded variant of the M2 Browning HB machine gun used during World War II is still in use today. Since the mid-1950s, some armored personnel carriers and utility vehicles have been made to withstand 12.7 mm machine gun fire, restricting the destructive capability of the M2. It still has more penetrating power than lighter weapons such as general-purpose machine guns, though it is significantly heavier and more cumbersome to transport. Its range and accuracy, however, are superior to light machine guns when fixed on tripods, and it has not been replaced as the standard caliber for Western vehicle-mounted machine guns (Soviet and CIS armored vehicles mount 12.7×108mm NSVs, which are ballistically similar to .50 BMGs).
Decades later, the .50 BMG was chambered in high-powered rifles as well. The Barrett M82 .50 caliber rifle and later variants were developed during the 1980s and have upgraded the anti-materiel power of the military sniper. A skilled sniper can effectively neutralize an infantry unit by eliminating several targets (soldiers or equipment) without revealing his precise location. The long range (over one mile) between firing position and target allows
.50 BMG