Behind the Bullet: .450 Bushmaster

posted on November 16, 2022
BTB 450 Bushmaster Lead

The modern sporting rifle—though I personally detest the term—is making in presence felt in the hunting fields more and more each year. And while the .223 Remington, .224 Valkyrie, 6.5 Creedmoor and .308 Winchester offer plenty of hunting opportunities, there are times where a hunter may wish for a little bit more bullet weight and/or frontal diameter. Looking to the big bores, you’ve got the .458 SOCOM, .50 Beowulf and the .450 Bushmaster; where the first two mentioned are surely heavy hitters, the .450 Bushmaster has the lowest velocity, but just might be the most flexible of the lot.

Federal Premium Fusion .450 Bushmaster ammunition.

The .450 Bushmaster was developed in 2007 by Tim LeGendre of LeMag Firearms, who then licensed his brainchild to Bushmaster Firearms International, though the original incarnation of his cartridge was known as the .45 Professional. Based on the .284 Winchester—which was a rebated-rim design to begin with—shortened to 1.700 inches and using a small rifle primer rather than the .284’s large rifle primer, the .450 Bushmaster is a straight-walled cartridge with the same .473-inch rim that works perfectly in the AR-10 platform.

With a body tapering from 0.500 inches to 0.480 inches at the case mouth, the .450 Bushmaster is designed to use the same 0.452”-diameter bullets that the .45 ACP, .45 Colt and .454 Casull use. Couple this with the cartridge’s use in the AR rifles as well as the bolt-action rifles being chambered for it—primarily to serve the needs of those hunters who are legally limited to straight-walled cartridges only for their deer and other big game species—and you’ve got a rather versatile package. Like the .45 ACP, 9mm and .40 S&W, the rimless (actually rebated rim) Bushmaster uses the case mouth for headspacing, so keep this in mind if you choose to reload for your rifle.

Hornady InterLock .450 Bushmaster cartridge.

The .450 Bushmaster is one of the cartridges derived from Col. Jeff Cooper’s “Thumper concept,” where he wanted a cartridge suitable for double duty in both defensive rifles, and in a hunting gun, where a heavier bullet of larger diameter would be employed to deliver one-shot kills when hunting larger game species. In retaining the .473-inch-diameter case head (common to the 7x57mm Mauser, .30-06 Springfield, .308 Winchester and so many more cartridges), the .450 Bushmaster rifle becomes more economical to manufacture, whether using the semi-auto AR platform or a bolt-action rifle platform. In the .452-inch-diameter, bullet weight will run from 185 grains (lighter in some instances) to over 300 grains, depending on the type of projectile. The beefy body precludes a double-stack within the confines of the AR-magazine, so you’re looking at a single-stack, with a ten-round 5.56-magazine holding five rounds, and the 30-round 5.56 mag holding 13 rounds.

Looking at the majority of the ammunition geared toward hunting, you’ll see the most popular bullet weights ranging between 250 and 300 grains. Velocities for the 250- to 260-grain loads will generally run at about 2200 fps, generating somewhere around 2,700 ft.-lbs. of energy, while the 300-grain ammunition will be moving at 1900 to 1950 fps, providing 2,400- to 2,500 ft.-lbs. of muzzle energy. Though the hollowpoint bullets will see their energy drop off rather quickly, the .450 Bushmaster will still deliver 1,000 ft.-lbs. of energy at 250 yards, even with the slower 300-grain loads.

450 Bushmaster cartridge head stamp.

Switch over to the polymer-tipped spitzer bullets—like the Winchester Extreme Point load in their Deer Season XP line or the FTX bullets in Hornady’s BLACK ammo line—and you’ll see and improvement in the trajectory figures. The 300-grain hollowpoint bullets will hit 6.1 inches high when zeroed at 200 yards, where the spitzers will hit just 4.1 inches high; the former is out of the vital zone, while the latter is not. Should you have the deer of a lifetime walk out and pose broadside at 300 yards, the 300-hollowpoint load will need 25.4 inches of holdover, where the 250-grain spitzer load will require 19.3 inches. I personally would avoid taking the .450 Bushmaster out that far, but the capability is certainly there.

Though seemingly a specialty cartridge—most useful as a hunting cartridge in those states which allow only straight-walled rifle cartridge to be used—the .450 Bushmaster has developed a considerable following, with most of the major ammunition manufacturers offering at least one load for the cartridge. Hornady has the 250-grain FTX bullet in the BLACK line, and the 245-grain InterLock spire point in the American Whitetail line, and loads the 395-grain FTX at a subsonic velocity in their SUBSONIC line. Federal loads the 300-grain jacketed hollowpoint in their ‘blue box’ Power-Shok line, and in the Non-Typical line. The Federal FUSION line features the 260-grain bonded-core bullet of the same name. Winchester offers a 250-grain Extreme Point polymer tip load and a 260-grain Power-Point cup-and-core bullet load. For those who prefer or are required to use lead-free projectiles, Barnes loads the 250-grain TSX in their VOR-TX ammo line.

Hornady American Whitetail .450 Bushmaster ammunition.

Invariably, it will be through handloading that the .450 Bushmaster will show its full-range of benefits, as the affordable and plentiful .45-caliber pistol bullets can be utilized for plinking, practice or for hunting/defensive applications. Look to a good small rifle primer—I usually reach for the Federal Gold Medal Match whenever I can get them, for the most uniform results—and for powders I prefer Hodgdon’s H110 or Accurate’s 5744. I like the Redding Seating Die with taper crimp, to best preserve the case mouth for headspacing, yet to equally keep my bullets exactly where I seat them, to best even out velocities. In my experiences with the Bushmaster, in both bolt guns as well as autoloaders, recoil is more than manageable, being more of that classic push than the violent slap associated with magnum cartridges.

Is the .450 Bushmaster an all-around cartridge that you’ll reach for when heading to Alaska for Dall sheep or take with you to Mexico for a trophy Coues deer? Probably not. But if you want a cartridge which will handle deer and bear at woods distances in any state, and which will absolutely flatten hogs at the feeder, while providing the capability of being a rock-solid defensive cartridge, the .450 Bushmaster should have a place near the top of the list.

Looking for previous installments of our "Behind the Bullet" series? We've got you covered.
7mm PRC
.275 Rigby
.340 Weatherby Magnum
.416 Ruger
27 Nosler
.257 Roberts
7mm Weatherby Magnum
 .300 PRC
.350 Rigby Magnum
.450 Nitro Express
.17 Hornet
7mm STW
6.8 Western
.375 Ruger
.223 Remington
• 6.5x55 Swedish
.416 Remington Magnum
.300 Winchester Short Magnum
28 Nosler
6.5 PRC
.22 WMR
.458 Winchester Magnum
.22 Hornet
.280 Ackley Improved
.240 Weatherby Magnum
.458 Lott
• .264 Winchester Magnum
• .348 Winchester
• .33 Nosler
• .260 Remington
• .30-30 Winchester
• .416 Rigby
 .358 Norma Magnum
• .22 LR
• 7mm-08 Remington
• 8mm Remington Magnum
• .338 Federal
• .224 Valkyrie
• .338-06 A-Square
• 9.3x62mm Mauser
• .257 Weatherby Magnum
• .45-70 Government
• .300 H&H Magnum
• .25-06 Remington 
• .30-06 Springfield
• 6.5 Creedmoor
• .300 Remington Ultra Magnum
• 7mm Remington Magnum
• .470 Nitro Express
• .280 Remington
• .300 Winchester Magnum
• .270 Winchester
• .222 Remington
• .45 ACP
• .404 Jeffery
• .44 Remington Magnum 
• .41 Remington Magnum
• .243 Winchester
• .338 Winchester Magnum
• .357 S&W Magnum
• 6.5-284 Norma
• 8x57 Mauser
• .38 Smith & Wesson Special
• 7x57mm Mauser
• 9mm Luger
• .35 Whelen
• .454 Casull
• .375 H&H Magnum
• .45 Colt
• .22-250 Remington
• 10mm Auto
• .308 Winchester


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