|Place of origin||USA|
|Parent case||.300 Remington Ultra Magnum/.404 Jeffery|
|Case type||Rimless, bottleneck|
|Bullet diameter||.338 in (8.6 mm)|
|Neck diameter||.371 in (9.4 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||122.5 gr H2O (7.94 cm3)|
|Primer type||Large rifle magnum|
338 Edge (.338/300 Ultra Mag, .338 Ultra Cat) is a Wildcat rifle cartridge based on the .300 Remington Ultra Magnum round necked up to accept 0.338" diameter bullets. It is gaining popularity as a long-range cartridge due to the wide availability of 0.338" projectiles that have a high ballistic coefficient. For instance, the 300-grain (19 g) Sierra Match King has a ballistic coefficient of 0.765 and is a popular choice for 338 Edge shooters.
The 338 Edge is similar in ballistics to the .338 Lapua Magnum, but can be chambered in a regular magnum action without modification, making it an attractive cartridge for shooters looking for the high performance of .338 Lapua Magnum without requiring a special or custom action.
Velocities in the 338 Edge are high, and the recoil can be substantial enough to make a rifle painful to shoot without a recoil reducing device such as a muzzle brake or suppressor. Recoil is approximately twice that of the popular .30-06 cartridge, for a given weight rifle.
- Carlock, Shawn. "338 Edge - History and Development". Len Backus' Long Range Hunting online magazine. Archived from the original on 1 November 2010. Retrieved 22 September 2010. CS1 maint: discouraged parameter (link)
- ".338 300 gr HPBT ballistics". Sierra Bullets. Archived from the original on 31 January 2019. Retrieved 1 February 2019.
- "338 Edge History & Development". Defensive Edge. Archived from the original on 2 July 2010. Retrieved 22 September 2010. CS1 maint: discouraged parameter (link)
- October 2000 issue of "The Accurate Rifle"