.308 Norma Magnum
Date: May 28 2014
Notes from the Lab: .308 Norma Magnum
The .308 Norma Magnum story began with the .458 Winchester Magnum, introduced in 1956. In 1958 Winchester introduced its .264 and .338 magnums on the .458 Winchester Magnum case necked down. All three were based on the .300/.375 H&H Magnum belted case, but shortened to function in a standard .30-06 length action. But when two years lapsed and Winchester failed to announce the same case necked to .30 caliber, wildcatters began necking the .338 case to .30 caliber, which became known as the .30-338.
The Swedish firm Norma used this opportunity to design its own cartridge, which was dimensionally very similar to the .30-338 with 25-degree shoulder etc. However, overall case length was slightly longer and there were other slight dimensional differences. At the time it was the only commercially available .30-caliber magnum designed for .30-06 length actions.
At first Norma offered brass cases and load data, followed more than a year later with commercially loaded ammunition. Norma also offered reamers to U.S. gunsmiths on a "loaner" basis, which were used to convert existing .30-06 rifles by re-chambering them. Several foreign rifle companies (including Browning, with the FN High Power) began offering the .308 Norma, which became popular. However, in 1963 Winchester announced the .300 Winchester Magnum, with its shoulder moved forward when compared to the .264 and .338 cases, in the Model 70. With domestic .300 Winchester Magnum rifles and ammunition readily available, demand for the Norma cartridge began to decline. Regardless, it is an excellent cartridge for hunting and long-range competition.
Ballistically, the .308 Norma Magnum is only slightly behind the .300 Winchester Magnum, with very little practical difference, especially with 180- through 220-grain bullets. Factory loaded ammunition and cases are still available from Norma USA.
The .308 Norma thrives on traditional magnum powders with notable accuracy and velocity being obtained with Accurate AAC-4350; IMR-4350, IMR-4831, IMR-7828; Alliant Reloder 19, Reloder 22, Reloder 25; Hodgdon H-1000; and Vihtavuori VV-N165.