.450 Bushmaster

History

The .450 Bushmaster is descended from the Thumper concept popularized by gun writer Jeff Cooper. Cooper was dissatisfied with the small-diameter bullet 5.56×45mm NATO (.223 Remington) of the AR-15, and envisioned a need for a large bore (.44 cal or greater) cartridge in a semi-automatic rifle to provide one-shot kills on big-game animals at 250 yards. Inspired by this, LeGendre developed his .45 Professional cartridge in the early 2000's and built and delivered an AR-10 in .45 Professional to Cooper.

After being sold the .45 Professional concept in 2007, Bushmaster requested the ammunition manufacturer Hornady to produce the .45 Professional cartridge for this project, but Hornady wanted to shorten the cartridge case and overall length to accommodate their 0.452 in. 250-grain pointed SST flex-tip bullet; plus .452 is a very common bullet size, being used by the .45 Colt, .45 ACP, .454 Casull, & .460 S&W Magnum, and the 250-grain SST was already a popular bullet for the .454 & .460. Bushmaster and LeGendre approved the change from a 1.772 in. (45 mm) case and 2.362 in. (60 mm) overall length (OAL) to the now standard 1.700 in. (43.18 mm) case and 2.260 in. (57.40 mm) OAL. This permitted operation in the more abundant and popular AR-15 platform, versus the larger less common AR-10 platform. Also, a name change to ".450 Bushmaster" was approved.

In 2006 the rights to the .450 Bushmaster were sold to Cerberus Capital Management, which eventually became part of Freedom Group, a company that also owned Remington Arms, Marlin Firearms, Advanced Armament Corporation (AAC) and others. Following Remington's bankruptcy in 2020 due to multiple lawsuits, the company's assets were sold off, with the .450 Bushmaster and its parent company being purchased by Nevada based Franklin Armory in 2021, best known for making the Binary Fire Control System.

Loadings and ballistics

The .450 Bushmaster makes use of .452 in. bullets because the lower impact velocities and energies would not adequately expand the heavier jacketed .458 in. bullets. The cartridge is chambered in bolt-action rifles by Ruger, Savage, Mossberg, and Remington. Ruger also chambers their Ruger No. 1 single shot rifle, and their AR-556 MPR rifle in .450, and Franklin Armory's XO-26 BFS-III equipped AR-15 pistol is chambered in .450. As of 2022, Bushmaster Firearms is once again manufacturing rifles chambered in the .450, including their original fixed-stock Bushmaster 20" barrel AR; the BOAR which also has a 20" barrel and features Magpul furniture including a UBR collapsible stock, pistol grip and M-LOK rail; and the Bravo Zulu AR which features a 16" barrel, Magpul MOE Carbine Stock & MLOK rail, and Bushmaster proprietary accessors like the DM2S® 2-stage trigger and Snake Charmer®II muzzle brake; all three models come with a 5-round magazine.

Ballistically, the .450 Bushmaster has a rather flat trajectory out to 200 yards, if the firearm is zeroed at 150 yards, the shooter can expect to see a rise of 2.2 inches at 100 yards (215 grain bullet), and a drop of 5.8 inches at 200 yards; although at this point it starts to drop off rather quickly, with the bullet dropping 32.8 inches at 300 yards. The cartridge fits single-stacked in a standard AR-15 magazine with a single-stack follower. A 10-round AR-15 magazine body yields a four-round magazine, a 20-round AR-15 magazine body yields a five- to seven-round magazine, and a 30-round body yields a nine-round magazine. As of 2025 Ammo Inc., Federal, Hornady, Remington, and Winchester manufacture ammunition for the rifle, and Starline manufactures empty brass for handloading.

References

References

1. (28 November 2007). "Bushmaster - Welcome to Bushmaster Firearms International".
2. (October 30, 2021). "Bushmaster firearms reintroduces the 450 bushmaster Rifle".
3. "CARTRIDGE and CHAMBER DRAWING - 450 BUSHMASTER".
4. [https://lynxdefense.com/450-bushmaster/#3-450-bushmaster-ballistics 450 Bushmaster Ballistic Chart] LynxDefense.com
5. (16 November 2022). "Behind the Bullet: .450 Bushmaster". [[National Rifle Association of America]].
6. (2012). "Cartridges of the World: A Complete Illustrated Reference for More Than 1,500 Cartridges". Gun Digest Books.
7. (2 May 2023). "450 Bushmaster: A Semi-Auto Hunting Powerhouse". © 2025 Free Range American.
8. (26 June 2016). "Big-Bore AR Cartridges". [[National Rifle Association of America]].
9. (3 August 2023). "50 Years Of Bushmaster Firearms". [[National Rifle Association of America]].
10. (27 September 2020). "Bankrupt Gun Maker Remington Outdoor to Be Broken Up and Sold". © [[Dow Jones & Company]], Inc..
11. (15 February 2021). "Bushmaster Announces a Comeback". © Guns.com.
12. "45 Cal .452 250 gr FTX (450 Bushmaster)".
13. "Ruger AR-556 MPR .450 Bushmaster". © [[ Sturm, Ruger & Co.]].
14. Pridgen, D.K.. "FRANKLIN ARMORY XO-26 .450 BUSHMASTER". Tactical-Life Magazine.
15. "BFSIII® EQUIPPED XO®-26 R4". © 2025 Franklin Armory®.
16. "Firearms - .450 BM". © 2025 Bushmaster® Firearms.
17. "BOAR™ 20"". © 2025 Bushmaster® Firearms.
18. "BRAVO ZULU™ 16"". © 2025 Bushmaster® Firearms.
19. (5 June 2025). "Head to Head: 400 Legend vs. .450 Bushmaster". [[National Rifle Association of America]].
20. (27 June 2018). "Lancer Magazine – 4 Round". Tromix Lead Delivery Systems.
21. "Duramag SS .450 Bushmaster (Stainless Steel)".
22. "AR-STONER Mag AR-15 450 Bushmaster 9-Round SS Black".
23. "Rifle Ammo - .450 Bushmaster". © [[Palmetto State Armory]].
24. ".450 Bushmaster Brass". © Starline Brass.