9×39mm

9×39mm
9×39mm SP-6 (7N9) cartridges with blue-tip armor-piercing bullets
Type	Rifle, subsonic
Place of origin	Soviet Union  Russia
Production history
Designer	Nikolai Zabelin
Designed	1980s
Specifications
Parent case	7.62×39mm
Case type	Rimless, bottleneck
Bullet diameter	9,25 (SP-5) 9,26 (SP-6)
Neck diameter	9.98 mm (0.393 in)
Shoulder diameter	10.36 mm (0.408 in)
Base diameter	11.35 mm (0.447 in)
Rim diameter	11.35 mm (0.447 in)
Rim thickness	1.50 mm (0.059 in)
Case length	38,76 (СП-5) 38,78 (СП-6)
Overall length	56 mm (2.2 in)
Ballistic performance
Bullet mass/type Velocity Energy 16.8 g (259 gr) 280 m/s (920 ft/s) 658.5 J (485.7 ft·lbf)

The 9×39mm is a Soviet / Russian rifle cartridge.

It is based on the Russian 7.62×39 mm round, but with an expanded neck to accommodate a 9 mm (.356 caliber) bullet. The cartridge was designed by N. Zabelin, L. Dvoryaninova and Y. Frolov of the in the 1980s. The intent was to create a subsonic cartridge for suppressed firearms for special forces units that had more power, range and penetration than handgun cartridges. The 5.45×39 mm cartridge introduced in 1974 for the AK-74 lacks sufficient bullet weight (at 53 gr to 80 gr) for acceptable energy at subsonic velocities. The bullet of the 9×39 mm is approximately 16 g (250 gr), double that of the normal 123 gr 7.62×39 mm round, and is subsonic. This slow velocity does not produce a sonic boom, but does limit the muzzle energy and effective range of a weapon when compared to non-suppressed assault rifles. The round has an effective lethal range of 300 to 400 meters and a maximum penetration of up to 8 mm of steel. Like the 5.45×39mm cartridge, 9×39mm SP-5 features an airpocket in the tip, which improves its capability to yaw after impact, and thus its effect in soft tissue.

Since the bullet weighs about twice as much as that of the 9×19mm Parabellum, its muzzle energy is about twice as high as that of a subsonic 9×19mm Parabellum bullet, e.g. when fired from a HK MP5SD.

SP-5 (7N8) - The SP-5 (СП-5) (SP: Spetsialnyj Patron; "Special Cartridge") was developed by Nikolai Zabelin. It is a conventional lead core FMJ bullet, but developed for accuracy.

SP-5UZ - The SP-5UZ (СП5-УЗ) is an SP-5 variant with an increased charge intended for a factory-specific strength testing of the weapons.

SP-6 (7N9) - The SP-6 (СП-6) was developed by Yuri Frolov. It has a hardened metal armor-piercing core. It can penetrate 2 mm (0.079 in) of steel at 500 meters or 6 mm (0.24 in) of steel, 2.8 mm (0.11 in) of titanium or 30 layers of Kevlar at 200 meters. At 100 meters it penetrates 8 mm (0.31 in) of steel, while retaining enough power to neutralize a soft target behind it.