.308 Norma Magnum (using Sierra bullets)
Date: Jul 11 2016
The .308 Norma Magnum story really began with the .458 Winchester Magnum, which was introduced in 1956. In 1958 Winchester introduced the .264 and .338 Magnums based on the .458 case necked down accordingly. All three cartridges were based on the .300/.375 H&H Magnum belted case, but shortened to function in a standard .30-06 length action, which made them the original “short magnums.” When two years lapsed and Winchester failed to announce the same case necked to .30 caliber, some wildcatters began necking the .338 case to .30 caliber, resulting in the .30-338.
The Swedish firm Norma took this window of opportunity to design its own cartridge, which was dimensionally very similar to the .30-338 with 25-degree shoulder, etc. Overall case length was slightly longer, however, and there were other slight dimensional differences. At the time it was the only commercially available .30-caliber magnum designed for “short” (.30-06 length) actions.
At first Norma offered brass cases and load data, then followed up more than a year later with commercial ammunition. The company loaned reamers to U.S. gunsmiths to convert existing .30-06 rifles by re-chambering them, then opening the bolt face and modifying the extractor as needed. Several foreign rifle companies (including Browning with its FN High Power rifle) began offering the .308 Norma cartridge, which became popular. In 1963 Winchester announced the .300 Winchester Magnum in its Model 70 (with the shoulder moved forward when compared to the .264 and .338 cases). With domestic .300 Winchester Magnum rifles and ammunition readily available in the U.S., demand for the Norma cartridge began to decline. Regardless, it is an excellent cartridge that has proven to offer outstanding accuracy in long-range competition and in the field.
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 unprimed cases are still available from Norma.
The .308 Norma thrives on traditional magnum powders with burn rates that are similar to 4350 and 4831.