.338 Remington Ultra Magnum

.338 Remington Ultra Magnum
338 Remingon Ultra Magnum.jpg
Place of originUSA
Production history
Parent case.300 Remington Ultra Magnum
Case typeBeltless, rebated, bottleneck
Bullet diameter.338 in (8.6 mm)
Neck diameter.371 in (9.4 mm)
Shoulder diameter.526 in (13.4 mm)
Base diameter.550 in (14.0 mm)
Rim diameter.534 in (13.6 mm)
Case length2.760 in (70.1 mm)
Overall length3.600 in (91.4 mm)
Case capacity113 gr H2O (7.3 cm3)
Rifling twist1-10 in (254 mm)
Primer typeLarge rifle magnum
Maximum pressure65,000
Ballistic performance
Bullet mass/type Velocity Energy
250 gr (16 g) PSP Bonded 2,860 ft/s (870 m/s) 4,540 ft⋅lbf (6,160 J)
250 gr (16 g) PSP A-Frame 2,860 ft/s (870 m/s) 4,540 ft⋅lbf (6,160 J)
Test barrel length: 26"

The .338 Remington Ultra Magnum is a .338 caliber rifle cartridge introduced by Remington Arms in 2002.


It is a beltless, rebated rim cartridge based on the .300 Remington Ultra Magnum[1] case shortened .090" and necked-up to accept a 0.338-inch (.338 caliber) bullet. The .338 Remington Ultra Magnum has a similar case capacity as the .338 Lapua Magnum[2] and somewhat lower than that of the .338-378 Weatherby Magnum. It is one of the most powerful .338-caliber rounds in production.

Because this cartridge already operates at very high pressures (65,000 PSI), handloaders cannot realize significant velocity improvements over factory ammunition as many handloaders have done over the years with more conventional, lower pressure rounds. However, they can still tune their own loads for best precision in their specific rifles, as with any other cartridge.

See also[]


  1. ^ .338 Rem Ultra Mag
  2. ^ "Lapua vs RUM Case Capacity". Archived from the original on 2014-07-26. Retrieved 2014-07-17.

External links[]