The .450 Marlin is a firearms cartridge

Cartridge (firearms)

A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 designed as a modernized equivalent to the venerable .45-70

.45-70

The .45-70 rifle cartridge, also known as .45-70 Government, was developed at the U.S. Army's Springfield Armory for use in the Springfield Model 1873...

 lever-action

Lever-action

Lever-action is a type of firearm action which uses a lever located around the trigger guard area, to load fresh cartridges into the chamber of the barrel when the lever is worked. Most lever-action firearms are rifles, but lever-action shotguns and a few pistols have also been made...

 cartridge. It was designed by a joint team of Marlin

Marlin Firearms

Marlin Firearms Co., formerly of North Haven, Connecticut, is a manufacturer of high power, center fire, lever action, and .22 caliber rimfire rifles. In the past, the company made shotguns, derringers and revolvers...

 and Hornady

Hornady

Hornady Manufacturing Company is an American manufacturer of ammunition and handloading components, based in Grand Island, Nebraska.The company was founded by Joyce Hornady in 1949 and is currently run by his son Steve Hornady who took over after his father's death in a plane crash in 1981.Hornady...

 engineers headed by Hornady's Mitch Mittelstaedt, and was released in 2000, with cartridges manufactured by Hornady and rifles manufactured by Marlin, mainly the Model 1895M levergun

Lever-action

Lever-action is a type of firearm action which uses a lever located around the trigger guard area, to load fresh cartridges into the chamber of the barrel when the lever is worked. Most lever-action firearms are rifles, but lever-action shotguns and a few pistols have also been made...

. The Browning BLR

Browning BLR

The Browning BLR is a lever action rifle manufactured by Browning Arms Company. It comes in many different variations and is chambered in calibers from .22-250 Remington to .325 WSM to .450 Marlin.- Differences :...

 is also now available in .450 Marlin chambering.

Design

While ballistically similar to the .45-70, the .450 Marlin was not developed from the .45-70. Rather, the .450 Marlin was developed from the wildcat .458x2 American

.458x2 American

The .458×2-inch American is a straight, belted, .458 caliber big bore cartridge designed by Frank Barnes. It is based on the .458 Winchester Magnum shortened to .-General Information:...

, which was based on the .458 Winchester Magnum

.458 Winchester Magnum

The .458 Winchester Magnum is a belted, straight-taper cased, dangerous game rifle cartridge. It was introduced commercially in 1956 by Winchester and first chambered in the Winchester Model 70 African rifle. It was designed to compete against the .450 Nitro Express and the .470 Nitro Express...

. This places the .450 Marlin in the .458 Winchester family of cartridges, though it is more easily understood as a "modernized" .45-70.

The belt has been modified to prevent it from chambering in smaller-bore 7mm Magnum or .338 Magnum rifles. The .45-70 and .450 Marlin cannot be cross-chambered, but rifles chambered for the .458x2 can be modified to fire the .450 Marlin.

Visually, the case resembles that of the .458 Winchester Magnum

.458 Winchester Magnum

The .458 Winchester Magnum is a belted, straight-taper cased, dangerous game rifle cartridge. It was introduced commercially in 1956 by Winchester and first chambered in the Winchester Model 70 African rifle. It was designed to compete against the .450 Nitro Express and the .470 Nitro Express...

with a wider belt. The cartridge is most useful for hunting big game at short ranges, being accurate at ranges of 150 yards.