.303 British / 7.7x57R
Originally adopted by British army in 1889, this cartridge remained in front-line service throughout British empire (later British Commonwealth) until late 1960s. Many surplus weapons chambered for this cartridge are still in civilian use, and commercial ammunition is still in limited production for those who own those old rifles.
Designation Bullet weight, g Muzzle velocity, m/s Muzzle energy, J Comments
Mk.II 14.6 640 2980 with round-nose FMJ bullet
Mk.VII 11.27 744 3120 with pointed FMJ bullet, from rifle barrel
Mk.VIII 11.27 777 3410 with pointed boat-tailed FMJ bullet, from machine gun