The .308 Norma Magnum (also .30-338 Magnum)
By Chuck Hawks
The .308 Norma Magnum is based on a .338 Win. Mag. case necked down to accept .308" diameter bullets. It is virtually identical to the .30-338 Magnum wildcat. The maximum case length is 2.559", the maximum cartridge overall length is 3.345", the rim diameter is .532", the shoulder angle is 25.5 degrees, and the neck is .317" long (more than one bullet diameter). The established maximum mean pressure for the .308 Mag. is 55,100 psi.
The .308 Norma Mag. is not currently loaded by the big U.S. ammo companies, but it is available from Norma. Norma factory loads for the .308 Magnum drive a 200 grain Vulkan bullet to a muzzle velocity (MV) of 2903 fps and muzzle energy (ME) of 3744 ft. lbs. At 200 yards the velocity is 2361 fps and the kinetic energy is 2476 ft. lbs.
Naturally, the .308 Norma is at its best with the slower burning powders. Reloaders can essentially equal the Norma factory load, and have access to many more bullet weights. Loading data can be found in most of the major reloading manuals.
According to the 26th edition of the Hodgdon Data Manual the .308 Mag. can drive a 150 grain bullet to a MV of 3090 fps with 79.0 grains of H1000 powder, and 3279 fps with 83.0 grains of H1000. A 165 grain bullet can be driven to MV of 2939 fps by 75.0 grains of H1000 powder, and 3123 fps by 79.0 grains of H1000. A 180 grain bullet can achieve a MV of 2769 fps in front of 72.0 grains of H1000 powder, and 2940 fps in front of 76.0 grains of the same powder. Hodgdon reports a pressure of 51,900 cup for the latter load. Velocities for all of the above loads were measured in a 26" barrel.
The sixth edition of the Hornady Handbook shows that their potent 220 grain InterLock bullet can be driven at a MV of 2300 fps by 60.5 grains of RL-25 powder, and to a MV of 2800 fps by a maximum charge of 75.1 grains of RL-25. The latter is 100 fps faster than the top velocity attainable with this bullet in the .300 Rem SAUM, .300 WSM, or .300 Win. Magnum. These Hornady loads used Norma brass, WLRM primers, and were tested in a rifle with a 24" barrel.
The reloader will find that the .308 Norma will handle bullets heavier than 180 grains every bit as well as (or better than) the .300 Win. Magnum, and considerably better than the new short .300 WSM and .300 Rem. SAUM cartridges. Due to its combination of standard length, a longer neck than most of its competitors, and excellent Norma brass, the .308 Norma Magnum may be the all-around best .300 Magnum cartridge for the dedicated reloader.
Note: Another article about the .308 Norma Magnum can be found on the Rifle Cartridge Page.
Copyright 2005, 2013 by Chuck Hawks. All rights reserved.