The .338 Norma Magnum cartridge was originally developed as a long-range sport shooting wildcat cartridge. It was introduced in 2008 and came into production in 2009.
In long range precision sport shooting rifles, which the .338 Norma Magnum cartridges were designed for, the chamber and throat area of the barrel are often custom made by a gunsmith for a particular cartridge, meaning the rifle (system) is consciously constructed for optimal use with a particular cartridge case and projectile combination. If projectiles with differing dimensions are to be used this will generally erode such a custom made system’s accuracy potential. This makes objective comparisons between cartridges hard, since cartridges are essential parts of a larger rifle system.
Since the .338 Lapua Magnum can be loaded to its C.I.P. overall length or even somewhat longer, the practical difference between the two cartridges gradually becomes negligible. Some manufacturers of .338 Lapua Magnum actions, magazines and rifles have indicated that they intend to offer products that will allow the use of .338 Lapua Magnum cartridges that can handle overall lengths that exceed the current C.I.P. .338 Lapua Magnum maximal overall length standard of 93.50 mm (3.681 in). – Wikipedia