12.7×55mm STs-130

The 12.7×55mm cartridge is used in some Russian firearms such as the VKS bullpup sniper rifle, the ShAK-12 bullpup battle rifle and the RSh-12 revolver. The cartridge can carry a projectile weighing between from 108 grains and 1173 grains and is predominantly used to fire heavy subsonic loads. The high penetration VKS round can penetrate up to 16 mm (0.63 in) of steel at 200 metres (220 yd) or body armor up to GOST 5 or NIJ III at 100 metres (110 yd). The accuracy of this cartridge when loaded with precision VKS bullets is claimed to be one MOA at 100 metres (110 yd) up to the effective range limit of 600 metres (660 yd).

12.7×55mm
From left to right, STs-130PT (sniper), STs-130PT2 (sniper with solid bronze bullet), STs-130VPS (high penetration / armor piercing).
Type	Rifle
Place of origin	Russian Federation
Production history
Designed	2002
Specifications
Parent case	.338 Lapua Magnum
Bullet diameter	13.01 mm (0.512 in)
Shoulder diameter	13.76 mm (0.542 in)
Base diameter	14.86 mm (0.585 in)
Case length	54.91 mm (2.162 in)
Overall length	97.3 mm (3.83 in)
Ballistic performance
Bullet mass/type Velocity Energy 59 g (911 gr) STs130PT 295 m/s (970 ft/s) 2,567 J (1,893 ft⋅lbf) 48.2 g (744 gr) STs130PT2 295 m/s (970 ft/s) 2,097 J (1,547 ft⋅lbf) 76 g (1,173 gr) STs130VPS 295 m/s (970 ft/s) 3,307 J (2,439 ft⋅lbf) 33 g (509 gr) STs130TP 300 m/s (980 ft/s) 1,485 J (1,095 ft⋅lbf) 17.94 g (277 gr) STs130BP 300 m/s (980 ft/s) 807.3 J (595.4 ft⋅lbf)

Despite being chambered in the same cartridge, the ShAK-12 (and RSh-12) would not be able to feed or chamber rounds designed for the VKS due to significant length differences in the bullet component of the cartridge and thus requires its own, shorter, loads. The ShAK-12 rounds have less range compared to the VKS with the maximum effective range of the loads reaching in between 100 and 300 metres (110 and 330 yd).