Reloading the .450 Bushmaster

The .450 Bushmaster was an attempt to improve the ballistic performance of AR-15 rifles, and reloading the .450 Bushmaster requires some special attention.

Reloading the .450 Bushmaster
Thanks to changes in some states’ hunting regulations, the .450 Bushmaster is gaining in popularity. It is certainly powerful and accurate enough for hunting deer.

Introduced by Bushmaster and Hornady in late 2007, the .450 Bushmaster was an attempt to improve the ballistic performance of AR-15 rifles. Launching a .45-caliber, 250-grain bullet at 2,200 fps is, of course, a significant performance step up compared to the 5.56 NATO’s relatively tiny 55-grain bullet exiting the barrel at 3,200 fps. At the time the .450 Bushmaster was introduced, not many folks hunted with an AR-style rifle.

Hornady was the only source for factory-loaded ammo at the time, but Remington and Federal later offered it. The round was slow to gain popularity and looked to be on a path to obsolescence, but a fortunate significant event occurred that saved the .450 Bushmaster from obscurity.

A few years ago, several states in the upper Midwest changed their hunting regulations. They decreed a straight-wall metallic cartridge larger than a specified caliber would be allowed to hunt whitetails. A dealer in Michigan convinced Ruger that adapting the American Ranch bolt-action rifle to chamber the .450 Bushmaster would be an excellent marketing move. Ruger has since shipped thousands of American Ranch rifles and recently introduced a second version of the AR-556 MPR autoloader chambered for the round.

Reloading Tips

I decided to investigate the performance of this big round and learned a few things about handloading it along the way. The .450 Bushmaster’s straight-wall case is slightly tapered, and the sizer die body is machined tool steel without a no-lube-required carbide or nitride insert. When reloading most rifle cartridges, I typically apply Redding case wax sparingly with my fingertips. With the .450 Bushmaster, I soon discovered each case needed just a light swipe of case lube to ensure the sizer die would reshape it properly without it getting stuck. A light application of Hornady One Shot spray lube or a swipe of Redding case wax worked well. Both lubes are easily removed after sizing by wiping with a cloth or tumbling in corncob media.


Reloading-450-Bushmaster-1

Although the .450 Bushmaster is a rifle cartridge, it is topped with pistol-size bullets of 0.452-inch diameter. And while there are many .45-caliber pistol bullets available, very few are constructed to accommodate the .450 Bushmaster’s velocities. Hornady’s 250-grain Flex Tip bullet was purposely designed for the .450 Bushmaster, and the Speer 300-grain Deep Curl bullet that’s designed for the .454 Casull is also suitable. I also included a prototype 260-grain Speer bullet that’s still in development.


The .450 Bushmaster’s case capacity is significantly greater than that of the 5.56 NATO/.223 Remington, but the cartridge uses Small Rifle primers to ignite the greater propellant charges. The .450 Bushmaster’s MAP (maximum average pressure) of 38,500 psi is only slightly greater than typical big-bore magnum handgun pressures, so it’s not surprising that it’s loaded with similar burn rate propellants. Since I would be firing half of the test loads in an AR, I chose to use CCI #41 mil-spec Small Rifle primers.

The Hornady die set includes a case mouth expander and a taper crimp die. When using either one, the operative phrase is “just a little is likely just enough.” You must expand the case mouth so the bullet heel will just seat and align itself properly when it’s inserted. Likewise, after seating the bullet to the desired cartridge overall length, a slight case mouth flare is evident. The taper crimp die should be adjusted to just barely iron the case mouth so it’s no longer expanded at all. There’s no shoulder or rim, so the round headspaces on the case mouth. Measurements indicated the case mouth diameter was typically reduced by a couple thousandths of an inch max.

I’ve never had to trim any other cartridge with a slightly tapered, straight-wall case, so I didn’t bother to check case length when reloading the fired brass two or three times. That was a lesson learned the hard way because it can be exciting when executing a GI-style extraction to clear a jam! You must check case length and trim cases when necessary.

Reloading-450-Bushmaster-2

Range Results

Using brand-new Ruger American Ranch and AR-556 rifles to test-fire factory-loaded ammo and my handloads, I found the Remington and Federal factory loads fired in the AR delivered similar 1.75-MOA to 2.0-MOA accuracy. However, my handloads weren’t quite as accurate. While velocities often matched or exceeded the comparable factory-ammo results, standard deviations were greater. However, the loads in both rifles were powerful and accurate enough to take down the next whitetail you encounter at ranges up to a couple hundred yards.


GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

Black Hills Evolution of Rifle Cartridge: .308 Win. 175 Gr. Match

Black Hills Evolution of Rifle Cartridge: .308 Win. 175 Gr. Match

David Fortier talks with Jeff Hoffman of Black Hills Ammunition about the evolution of the .308 Win. 175 Gr. Match bullet.

Tactical Solutions Introduces New X-Ring Takedown SBR Rifle

Tactical Solutions Introduces New X-Ring Takedown SBR Rifle

Keith Feeley of Tactical Solutions sat down with Michael Bane at SHOT Show 2018 to talk about the new X-Ring Takedown SBR .22LR rifle.

Hornady 6MM Creedmoor

Hornady 6MM Creedmoor

Tom Beckstrand and Neal Emery of Hornady highlight the 6MM Creedmoor ammo.

The Glock 21

The Glock 21

Frank and Tony from Gallery of Guns spice up the Glock test using their non-dominant hands.

See More Popular Videos

Trending Articles

Crimson Trace enters the riflescope business with the Crimson Trace CTL-3420 4-20X 50mm. Optics

Review: Crimson Trace CTL-3420 4-20X 50mm

Joel J. Hutchcroft - April 29, 2019

Crimson Trace enters the riflescope business with the Crimson Trace CTL-3420 4-20X 50mm.

The new Bushnell FORGE riflescope is “the only choice for long-range hunting enthusiasts.” Optics

Review: Bushnell FORGE 4.5-27X 50mm

Sam Wolfenberger - May 01, 2019

The new Bushnell FORGE riflescope is “the only choice for long-range hunting enthusiasts.”

Daniel Defense has blazed a new trail with its first-ever bolt-action rifle, the Daniel Defense Delta 5. Rifles

Daniel Defense Delta 5 Review

Joel J. Hutchcroft - May 31, 2019

Daniel Defense has blazed a new trail with its first-ever bolt-action rifle, the Daniel...

Is the SIG P320 9mm modular pistol the best polymer-frame high-capacity sidearm ever designed? Let's find out. Handguns

SIG P320 9mm Review

Joseph Von Benedikt - September 13, 2018

Is the SIG P320 9mm modular pistol the best polymer-frame high-capacity sidearm ever designed?...

See More Trending Articles

More Reloading

By cleverly increasing the parent cartridge's powder capacity, the .30-06 Ackley Improved wildcat provides higher velocities. Reloading

Handloading the .30-06 Ackley Improved

Lane Pearce - February 21, 2020

By cleverly increasing the parent cartridge's powder capacity, the .30-06 Ackley Improved...

Successfully handloading for a 308 AR hinges on determining just the right amount of a compatible propellant. Reloading

308 Load Data for ARs

Lane Pearce - September 30, 2019

Successfully handloading for a 308 AR hinges on determining just the right amount of a...

Handloading the increasingly popular .450 Bushmaster requires some special attention. Reloading

Reloading the .450 Bushmaster

Lane Pearce - November 15, 2019

Handloading the increasingly popular .450 Bushmaster requires some special attention.

Where too little pressure can cause as much trouble as too much pressure, the short .44 Russian and .45 Schofield cases offer a compelling benefit. Reloading

.44 Russian, .45 Schofield Case Capacity

Allan Jones - September 09, 2019

Where too little pressure can cause as much trouble as too much pressure, the short .44...

See More Reloading

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Get Digital Access.

All Shooting Times subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now