.450 Bushmaster

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.450 Bushmaster
.450 Bushmaster (left), .223 Remington (right)
Place of originUnited States
Production history
DesignerLeMAG Firearms LLC
Parent case.284 Winchester
Case typeRebated, straight
Bullet diameter.4520 in (11.48 mm)
Land diameter.4420 in (11.23 mm)[3]
Neck diameter.4800 in (12.19 mm)[3]
Base diameter.5000 in (12.70 mm)[3]
Rim diameter.4730 in (12.01 mm)[3]
Rim thickness.0540 in (1.37 mm)[3]
Case length1.700 in (43.2 mm)[3]
Overall length2.260 in (57.4 mm)[3]
Case capacity59.5 gr H2O (3.86 cm3)
Maximum pressure (SAAMI)38,500 psi (265 MPa)
Ballistic performance
Bullet mass/type Velocity Energy
250 gr (16 g) SST 2,214 ft/s (675 m/s) 2,722 ft⋅lbf (3,691 J)
260 gr (17 g) AccuTip 2,180 ft/s (660 m/s) 2,744 ft⋅lbf (3,720 J)
250 gr (16 g) FTX Hornady BLACK 2,200 ft/s (670 m/s) 2,686 ft⋅lbf (3,642 J)
Test barrel length: 20 in (508 mm)
Source(s): Lynx Defense[4]
The .450 Bushmaster was developed for big game hunting with modern rifles.

The .450 Bushmaster (11.48x43mmRB) is a rifle cartridge developed by Tim LeGendre of LeMag Firearms, and licensed to Bushmaster Firearms International. The .450 Bushmaster is designed to be used in standard M16s and AR-15s, using modified magazines and upper receiver assemblies.


The .450 Bushmaster is descended from the Thumper concept popularized by the gun writer Jeff Cooper. Cooper was dissatisfied with the small-diameter 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,[when?] and later[when?] built and delivered an AR-15 in .45 Professional to Cooper.[5]

Bushmaster requested[when?] 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. 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 AR-10 platform. Also, a name change to ".450 Bushmaster" was approved.[citation needed]

Loadings and ballistics[edit]

.450 Bushmaster single-stacks in magazines, unlike .223, which sits in two staggered columns
.450 Bushmaster cartridges and components

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.[6] The cartridge is chambered in bolt-action rifles by Ruger, Savage, Mossberg, and Remington, Ruger's No. 1 single shot rifle, AR-15 rifles, as well as an AR-15 pistol by Franklin Armory.[7]

Ballistically, the .450 Bushmaster has a rather flat trajectory out to 200 yards; if the firearm is zeroed at 150 yards, the user can expect to see a rise of 1.8 inches at 100 yards, zero at 150 yards, and a drop of 4.9 inches at 200 yards.[citation needed] 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 [8] magazine, a 20-round AR-15 magazine body yields a five- to seven-round [9] magazine, and a 30-round body yields a nine-round [10] magazine. Hornady, Remington and Federal now manufacture ammunition for the rifle, and Starline manufactures empty brass for handloading.

See also[edit]


  1. ^ "Bushmaster - Welcome to Bushmaster Firearms International". 28 November 2007. Archived from the original on 2007-11-28. Retrieved 12 November 2021.
  2. ^ GUNSweek. (2021, October 30). Bushmaster firearms reintroduces the 450 bushmaster Rifle. GUNSweek.com. Retrieved May 5, 2023, from https://www.gunsweek.com/en/rifles/news/bushmaster-firearms-reintroduces-450-bushmaster-rifle
  3. ^ a b c d e f g "CARTRIDGE and CHAMBER DRAWING - 450 BUSHMASTER" (PDF). SAAMI. p. 147. Archived from the original (PDF) on 2018-08-22. Retrieved 2018-08-22.
  4. ^ 450 Bushmaster Ballistic Chart LynxDefense.com
  5. ^ Barnes, Frank C. (2012). Cartridges of the World: A Complete Illustrated Reference for More Than 1,500 Cartridges. Gun Digest Books. pp. 97–. ISBN 978-1-4402-3059-2.
  6. ^ "45 Cal .452 250 gr FTX (450 Bushmaster)". Hornady. Archived from the original on 2017-07-10. Retrieved 2016-08-13.
  7. ^ Pridgen, D.K. "FRANKLIN ARMORY XO-26 .450 BUSHMASTER". Tactical-Life Magazine. Retrieved 26 Feb 2014.
  8. ^ "Lancer Magazine – 4 Round - Tromix Lead Delivery Systems". Tromix.com. 27 June 2018. Archived from the original on 17 October 2021. Retrieved 8 December 2019.
  9. ^ "Duramag SS .450 Bushmaster (Stainless Steel)". Duramag. Archived from the original on 2019-12-08. Retrieved 2019-12-08.
  10. ^ "AR-STONER Mag AR-15 450 Bushmaster 9-Round SS Black". Midwayusa.com.

External links[edit]