.303/25

.303/.25
Type	Rifle
Place of origin	Australia
Production history
Designed	1940s
Specifications
Parent case	.303 British
Case type	Rimmed, bottleneck
Bullet diameter	0.257 in (6.5 mm)
Neck diameter	0.290 in (7.4 mm)
Shoulder diameter	0.412 in (10.5 mm)
Base diameter	0.460 in (11.7 mm)
Rim diameter	0.540 in (13.7 mm)
Rim thickness	.060 in (1.5 mm)
Case length	2.185 in (55.5 mm)
Overall length	2.85 in (72 mm)
Case capacity	50.86 gr H2O (3.296 cm3)
Rifling twist	1-12 inches
Primer type	Large rifle [1]
Ballistic performance
Bullet mass/type Velocity Energy 87 gr (6 g) SP 3,010 ft/s (920 m/s) 1,750 ft⋅lbf (2,370 J) 100 gr (6 g) HPBT 2,800 ft/s (850 m/s) 1,740 ft⋅lbf (2,360 J) 117 gr (8 g) SP 2,800 ft/s (850 m/s) 2,030 ft⋅lbf (2,750 J)
Test barrel length: 24

The .303/25, sometimes known as the .25/303 is a wildcat centrefire rifle cartridge, based on the .303 British, necked down to fire a .257 projectile, originating in Australia in the 1940s as a cartridge for sporterised rifles, particularly on the Lee–Enfield action; similar versions also appeared in Canada around the same time.^[2]