History of the 450 Marlin Cartridge

The 450 Marlin cartridge was developed as a "modern" replacement for the 45-70 Government cartridge. This is not to imply that modern 45-70 rifles and ammunition are not being made today. However, the 45-70 cartridge dates back to 1873 and was originally used with black powder rather than modern smokeless powder. Chamber pressures were not standardized, and there was no guarantee that older rifles could handle the pressue that modern rifles could. As a result, factory ammunition does not live up to the potential of modern rifles, and handloaders take matters into their own hands by creating loads that produce more pressure than the SAAMI specification allows.

45-70 Government and 450 Marlin cartridges

The creation of the 450 Marlin cartridge eliminates all of this mystery. It takes into consideration the capabilities of modern firearms, and like all modern cartridges, it had an official pressure specification from day one. The 450 Marlin has the same bore diameter and uses the same bullets as the 45-70. The two cartridges have nearly the same case capacity. The 450 Marlin should be able to do anything the 45-70 can do and vice versa.

The 450 Marlin was designed specifically for use in lever-action rifles with tubular magazines, and requires a flat-nose bullet. Externally, the 450 Marlin differs from the 45-70 in that it is a rimless, belted cartridge, whereas the 45-70 is a rimmed cartridge. Some people will refer to the 450 Marlin as a shortened 458 Winchester, and indeed, it has the same head dimensions and can trace its lineage back to the 458 Winchester and the 300 and 375 H&H Magnum — as is the case with all belted magnums. However, this cartridge was given an extra-wide belt to prevent it from chambering in other firearms.

The development of the 450 Marlin cartridge was a joint effort between Marlin and Hornady (led by Mitch Mittelstaedt of Hornady), and it was introduced in 2000. Hornady is currently the only factory producing ammunition for this cartridge, and they produce only two types: the 350 grain Interlock, which is supposed to reach 2100 fps in a 22 inch barrel, and the 325 grain LEVERevolution.

SAAMI lists the maximum average pressure at 43500 psi.