7.62×53mmR

7.62×53mmR
7.62×53mmR cartridges
Type	Rifle
Place of origin	Finland
Service history
In service	1918 to present
Used by	Finland
Production history
Designed	1918
Produced	1918 to present
Specifications
Parent case	7.62×54mmR
Case type	Rimmed, necked
Bullet diameter	7.85 mm (0.309 in)
Neck diameter	8.55 mm (0.337 in)
Shoulder diameter	11.61 mm (0.457 in)
Base diameter	12.42 mm (0.489 in)
Rim diameter	14.40 mm (0.567 in)
Rim thickness	1.60 mm (0.063 in)
Case length	53.50 mm (2.106 in)
Overall length	77.00 mm (3.031 in)
Case capacity	4.16 cm3 (64.2 gr H2O)
Rifling twist	300 mm (1 in 11.81 in)
Primer type	Berdan
Maximum pressure	390.00 MPa (56,565 psi)
Ballistic performance
Bullet mass/type Velocity Energy 185.4 gr (12 g) FMJ 812 m/s (2,660 ft/s) 3,960 J (2,920 ft·lbf)

The 7.62×53mmR (also known as the 7.62×53mmR Finnish) rifle cartridge is a Finnish design based on the Russian 7.62×54mmR round dating back to 1891.

After gaining its independence in 1917 and after the Finnish Civil War of 1918, large numbers of Model 1891 Mosin–Nagant rifles were in the hands of the Finnish military. As the old barrels were worn out, they were replaced by new 7.83 mm (.308 in) barrels and the leftover 7.62×54mmR cartridges being in short supply, a domestic product was needed. This gave birth to the 7.62×53mmR.

In the late 1930s the Finnish Army started loading military cartridges with domestically produced 7.87 mm (.310 in) diameter D166 bullets as the production of new M39 "Ukko-Pekka" rifles barreled for 7.62×54R diameter bullets started. This change was due in part to allow the use of captured Soviet ammunition and machine gun ammunition which often was of a slightly greater bore diameter than its Finnish counterparts. The rifling twist rate was also changed from 300 mm (1 in 11.81 in) to 254 mm (1 in 10 in).

The 7.62×53mmR cartridge remains in military use to this day, although it is now only used by the 7.62 TKIV 85 sniper rifle. PKM machine guns and other Russian weapons in use by the Finnish Defence Forces use the 7.62×54mmR exclusively. The Finnish Defence Forces issued instructions that when ever possible, personnel issued with a rifle chambered for 7.62×53mmR (effectively the TKIV 85 rifle) should use 7.62×53mmR ammunition only, and that use of 7.62×54mmR is only allowed when 7.62×53mmR is not available.

The 7.62×53mmR has 4.16 ml (64 grains) H₂O cartridge case capacity. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt action rifles and machine guns alike, under extreme conditions.