5.45×39mm PSP

The 5.45×39mm PSP cartridge is a rimless bottlenecked intermediate cartridge. It was introduced into service in 2005 together with ADS amphibious rifle by Russia. This special cartridge was made for underwater use in ADS rifle and based on standard 5.45×39mm.

5.45×39mm PSP
5.45×39mm PSP cartridge
Type	Rifle
Place of origin	Russia
Service history
In service	2005–present
Used by	Russian Federation
Production history
Designer	KBP Instrument Design Bureau
Designed	2005
Specifications
Case type	Steel, rimless, bottleneck
Bullet diameter	<5.60mm (subcaliber)
Neck diameter	6.29 mm (0.248 in)
Shoulder diameter	9.25 mm (0.364 in)
Base diameter	10.00 mm (0.394 in)
Rim diameter	10.00 mm (0.394 in)
Rim thickness	1.50 mm (0.059 in)
Case length	39.82 mm (1.568 in)
Overall length	57.00 mm (2.244 in)
Case capacity	1.74 cm3 (26.9 gr H2O)
Rifling twist	255 mm (1 in 10 inch) or 200 mm (1 in 7.87 inch)
Primer type	Berdan
Maximum pressure	380.00 MPa (55,114 psi)
Ballistic performance
Bullet mass/type Velocity Energy 16.4 g (253 gr) PSP Tungsten bullet 333 m/s (1,090 ft/s) 909 J (670 ft⋅lbf) 14.5 g (224 gr) PSP-UD Bronze bullet 430 m/s (1,400 ft/s) 1,340 J (990 ft⋅lbf)
Test barrel length: 418 mm (16.5 in) ADS amphibious rifle

There are two variants of it. PSP with heavy 16.4g tungsten alloy bullet and PSP-UD with 14.5g bronze bullet.^[1][2] The bullets are saboted and very deeply seated to stay within overall length specs.