5.8×42mm

The 5.8×42mm / DBP87 ("Dàn (弹) Bùqiāng (步枪) Pŭtòng (普通), 1987"; literally "Standard Rifle Cartridge, 1987") is a military rimless bottlenecked intermediate cartridge developed in the People's Republic of China. There is limited information on this cartridge, although the People's Liberation Army says that it is superior to the 5.56×45mm NATO and 5.45×39mm Soviet cartridges. Another variant called the DBP88 “heavy round” was designed specifically for squad automatic weapons and designated marksman rifles. The 5.8×42mm “heavy round” cartridge has the same dimensions as the standard 5.8×42mm cartridge, but utilizes a longer streamlined bullet with a heavy steel core for increased performance at extended ranges and penetration. As of 2010 all 5.8×42mm cartridge variants are gradually succeeded by the DBP10 variant.

History
China started development of the 5.8×42mm cartridge in 1979 and finalized the cartridge in 1987. The 5.8×42mm / DBP87 was designed to replace the Soviet 7.62×39mm cartridge used by the People's Liberation Army (PLA). The Type 95 / QBZ-95 (Chinese: 轻武器,步枪,自动, 1995; Pinyin: Qīng wǔqì, Bùqiāng, Zìdòng, 1995; literally "Light weapon, Rifle, Automatic, 1995") 5.8 mm caliber assault rifle, firing the 5.8×42mm / DBP87 or the improved DBP95, is now the standard issue weapon in the PLA. The DBP87 service round was quickly supplemented in 1988 by the DBP88 round which was loaded with a heavier more aerodynamic projectile for improved extended range performance.

The 5.8×42mm is an example of an international tendency towards relatively small sized, light weight, high velocity military service cartridges. Cartridges like the American 5.56×45mm NATO, Soviet 5.45×39mm and 5.8×42mm allow a soldier to carry more ammunition for the same weight compared to their larger and heavier predecessor cartridges, have favourable maximum point-blank range or "battle zero" characteristics and produce relatively low bolt thrust and free recoil impulse, favouring light weight arms design and automatic fire accuracy.

In June 2004, an improved version of the 5.8×42mm cartridge entered development as the matching ammunition for the revised assault rifle, Type 95-1. Both designs were finalized in 2010 and production began the same year. This new cartridge is known as DBP10.

To improve accuracy and barrel life the barrel was also redesigned. The number of rifling grooves was increased from 4 to 6. The diameter of the lands was slightly increased from 5.8 to 5.84 mm to 5.82 to 5.86 mm. The groove diameter was decreased from 6.01 to 6.07 mm to 5.98 to 6.02 mm. In addition, the twist rate in the revised 95-1 assault rifle was reduced from 240 mm to 210 mm.

The People's Liberation Army claims that the 5.8×42mm is superior to the 5.56×45mm NATO SS109 and the 5.45×39mm 7N6; stating it has better armor penetration of 10 mm at 300 meters, a flatter trajectory, and a higher retention of velocity and energy downrange.

5.8×42mm cartridge variants
The DBP87/95 cartridge with 4.15 g bullets has a muzzle velocity of 930 m/s from a standard barrel (Type 95 / QBZ-95, 463 mm barrel length), and 940 to 960 m/s from the Type 95 LSW (557 mm barrel length). The bullet has a ballistic coefficient (G7 BC) of approximately 0.156. The steel core has a diameter of 4.1 mm. In order to save cost, several compromises were made. In particular, the cartridge case is made of steel, which is cheaper than brass. To reduce the chance of rust, the case is covered in a thin layer of protective paint in dark brown. Steel is less flexible than brass and therefore does not fill the chamber cavity as well when fired, decreasing the performance. A cleaner-burning propellant and a non-corrosive primer is used for the DBP-87.

The DBP88 “heavy round” cartridge has a 5 g bullet and a muzzle velocity of 870 m/s from a standard barrel (Type 95 / QBZ-95, 463 mm barrel length), and 940 to 960 m/s from the Type 95 LSW / Type 95 SAW / QBB-95 (557 mm barrel length), and 895 m/s from the Type 88 / QBU-88 (620 mm barrel length). The bullet has a ballistic coefficient (G7 BC) of approximately 0.210. It has an effective range of 800 m and can penetrate 3 mm steel plates at a distance of 1000 m. It is reported to have very good accuracy at 600 m.

The newest DBP10 cartridge variant has a hardened steel-cored 4.6 g bullet and a muzzle velocity of 915 m/s and is designed to match all currently serving 5.8×42mm chambered weapons. The bullet has a ballistic coefficient (G7 BC) of approximately 0.193. It will replace all previous DBP87/95 and DBP88 5.8×42mm rounds. Major improvements include a non-corrosive primer, a copper-coated steel case with a copper alloy bullet jacket with a 3.8 mm diameter hardened steel core for better penetration of (body) armor. It also uses a cleaner burning propellant so as not to leave residue inside the weapon after firing. However, although testing of the previous DBP87/95 5.8 mm rounds showed that they were less likely to cause serious wounds, the issue was not addressed with the new DBP10 round. DBP10 has an operating pressure of 255 to 289.4 MPa. The DBP10 cartridge weighs 12.9 g. Accuracy of fire at 300 m (R50) is stated as 75 mm, at 600 m (R50) is stated as 140 mm and at 800 m (R50) is stated as 230 mm. R50 at a specific range means the closest 50 percent of the shot group will all be within a circle of the mentioned diameter at that range. The circular error probable method employed by the Chinese and other (European) militaries cannot be converted and is not comparable to the common US methods (groupsize of 5 or 10 successive shots fired at 100 yards) for determining accuracy.

A new match round has been designed for QBU-88 designated marksman rifle to improve the rifle's complained accuracy, though no official information has been given.

Use

 * Chinese Type 87 assault rifle
 * Chinese Type 95 / QBZ-95 assault rifle
 * Chinese Type 95B / QBZ-95B carbine
 * Chinese Type 95 LSW / Type 95 SAW / QBB-95 light support weapon / squad automatic weapon
 * Chinese Type 88 / QBU-88 sniper rifle
 * Chinese Type 03 / QBZ-03 assault rifle
 * Chinese Type 88 / QJY-88 light machine gun
 * Chinese Carbine portion ZH-05