12.7×108mm

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12.7×108mm
12.7x108mm.jpg
A 12.7×108mm cartridge
Type Heavy machine gun
Place of origin  USSR
Service history
In service 1934–present
Used by Soviet Union and successor states
Wars Winter War, World War II, Korean War, Portuguese Colonial War, Vietnam War, Cambodian Civil War, Cambodian–Vietnamese War, Six-Day War, War of Attrition, Yom Kippur War, Soviet war in Afghanistan, Iran–Iraq War, Gulf War, Chechen War, Iraq War, War in Afghanistan, Libyan Civil War, Syrian civil war, many others
Specifications
Bullet diameter 12.98 mm (0.511 in)
Neck diameter 13.95 mm (0.549 in)
Shoulder diameter 18.90 mm (0.744 in)
Base diameter 21.75 mm (0.856 in)
Rim diameter 21.70 mm (0.854 in)
Rim thickness 1.90 mm (0.075 in)
Case length 108 mm (4.3 in)
Overall length 147.50 mm (5.807 in)
Case capacity 22.72 cm3 (350.6 gr H2O)
Maximum pressure 360 MPa (52,000 psi)
Ballistic performance
Bullet weight/type Velocity Energy
48.3 g (745 gr) API B32 820 m/s (2,700 ft/s) 16,240 J (11,980 ft⋅lbf)
55.4 g (855 gr) API BS 820 m/s (2,700 ft/s) 18,625 J (13,737 ft⋅lbf)
Source(s): world.guns.ru

The 12.7×108mm cartridge is a heavy machine gun and anti-materiel rifle cartridge used by the former Soviet Union, the former Warsaw Pact, modern Russia, and other countries.

It is used in the same roles as the NATO .50 BMG (12.7×99mm NATO) cartridge. The two differ in bullet shape and weight, and the casing of the 12.7×108mm is slightly longer and thicker, allowing it to hold slightly more of a different type of powder. The 12.7×108mm can be used to engage a wide variety of targets on the battlefield, and will destroy unarmored vehicles, penetrate lightly armored vehicles and damage external ancillary equipment (i.e.: searchlights, radar, transmitters, vision blocks, engine compartment covers) on heavily armored vehicles such as tanks.[1] Armor-piercing .50 cal ammunition will penetrate around 25 mm of armor. Normal full metal jacket .50 cal ammunition will only dimple tank armor, causing no damage.

Cartridge dimensions

The 12.7×108mm has 22.72 ml (350 grains) H2O cartridge case capacity.

12,7 x 108.jpg

12.7×108 maximum cartridge dimensions. All sizes in millimetres (mm).

Americans would define the shoulder angle at alpha/2 ≈ 18.16 degrees.

According to guidelines the 12.7×108mm case can handle up to 360 MPa (52,213 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum CIP pressure to certify for sale to consumers.

Incorrect interchangeability claims

It is often claimed that the US .50 BMG (12.7×99mm NATO) cartridge can be fired in Soviet/Russian 12.7×108mm machine guns. The 12.7×108mm was even called a “.51-caliber.” This often claimed interchangeability is an assumption made from[dubious – discuss] the 12.7×108mm being listed as “.511-caliber” in US intelligence publications during the Vietnam War. The bullets used for both cartridges are ~.51 inches in diameter. .50 caliber, 1/2 of an inch, is the diameter of the hole bored down the barrel of the gun first. Then rifling is cut all around the bored hole to a depth of .005". Thus, .500 + .005 + .005 = .510." Upon firing the bullet engages the rifling, and .005" grooves are pressed into the surface of the bullet to impart spin to stabilize the bullet. Despite the similar bullet diameters, the dimensional differences between the two cartridges would prevent either being correctly chambered in a firearm designed for the other.

Partial list of 12.7×108mm firearms

See also

References

  1. ↑ Technical Intelligence Bulletins May - June 2003
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Further reading

  • Борцов А.Ю. "Пятилинейный", Мастер-ружье issue 110, May 2006, pp. 56–62

External links

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