The .450 Marlin grew out of an attempt to create a modernized version of the venerable .45-70 cartridge. While the .45-70 can be loaded to higher pressures in order to offer impressive ballistic performance, those hot loads can destroy older firearms that can’t handle them. The .450 Marlin allows shooters to replicate hot .45-70 performance, but without the potential danger of blowing up a 100-year-old firearm.
The .450 Marlin wasn’t developed from the .45-70, but rather from the wildcat .458×2” American, itself a derivative of the .458 Winchester Magnum. The .450 Marlin’s case is slightly longer than the 2” wildcat, at 2.1”. Overall cartridge length is 2.55”, the same length as the .30-30 Winchester and just slightly longer than the .38-55 Winchester. That allows it to be chambered in lever action rifles that can handle those cartridges. The .450 Marlin can also be chambered in bolt-action rifles, just like its grandfather the .458 Win. Mag.
The .450 Marlin offers plenty of performance, being able to push 300-grain bullets to 2,300 feet per second and 400-grain bullets to 2,000 feet per second, at relatively low maximum pressures of around 42,000 psi, for muzzle energy of about 3,500 foot-pounds. In theory, if the cartridge could be loaded to 55,000 psi, say in a bolt-action rifle, it should be capable of pushing the 400-grain bullets to 2,200 feet per second, for about 4,300 foot-pounds of muzzle energy.
Even at standard pressure loading, the .450 Marlin is more than capable of taking any game in North America. Unfortunately for shooters, the production of .450 Marlin lever action rifles was stopped by Marlin a decade ago. While reloading accessories are still available here and there, factory ammunition is nearly non-existent. At this point, the cartridge is basically a handloading only proposition.
If you own a rifle in .450 Marlin, you likely know that it’s a capable performer. But you likely also know that you need to start stocking up on reloading accessories. If you don’t already own a .450 Marlin, unless you’re prepared to handload for the cartridge and stock up on enough cases to last you a lifetime, you may want to look at other cartridges for your survival needs.