.300 Remington Ultra Magnum

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.300 Remington Ultra Magnum
.300 RUM cartridge
Type	Rifle
Place of origin	Canada
Production history
Designer	Remington
Designed	1999
Manufacturer	Remington Arms Company
Produced	1999–present
Specifications
Parent case	.404 Jeffery
Case type	cartridge, center fire primer, bottleneck
Bullet diameter	.308 in (7.8 mm)
Neck diameter	.344 in (8.7 mm)
Shoulder diameter	.525 in (13.3 mm)
Base diameter	.550 in (14.0 mm)
Rim diameter	.534 in (13.6 mm)
Case length	2.850 in (72.4 mm)
Overall length	3.600 in (91.4 mm)
Case capacity	110.2 gr H2O (7.14 cm3)
Rifling twist	1–10"
Primer type	Large rifle magnum
Maximum pressure	65,000 psi (450 MPa)
Ballistic performance
Bullet mass/type Velocity Energy 150 gr (10 g) X 3,456 ft/s (1,053 m/s) 3,979 ft⋅lbf (5,395 J) 168 gr (11 g) BTHP 3,295 ft/s (1,004 m/s) 4,051 ft⋅lbf (5,492 J) 180 gr (12 g) BTSP 3,229 ft/s (984 m/s) 4,168 ft⋅lbf (5,651 J) 200 gr (13 g) SP 3,067 ft/s (935 m/s) 4,178 ft⋅lbf (5,665 J) 220 gr (14 g) RN 2,933 ft/s (894 m/s) 4,203 ft⋅lbf (5,699 J)
Test barrel length: 24" (610 mm) Source(s): Accurate Powder[1]

The .300 Remington Ultra Magnum, also known as the .300 Ultra Mag, 7.62×72mm or .300 RUM, is a 7.62 mm (.308 inch) rifle cartridge introduced by Remington Arms in 1999. The .300 Remington Ultra Magnum is one of the largest commercially available .30 caliber magnums currently being produced. It is a beltless, rebated rim cartridge, capable of handling all large North American game, as well as long-range shooting. Among commercially produced .30-caliber rifle chamberings, the .300 Remington Ultra Magnum is second only to the .30-378 Weatherby Magnum in cartridge-case capacity.