.450 Bushmaster

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.450 Bushmaster
450 BM + 223.jpg
.450 Bushmaster (left), .223 Remington (right)
Type Rifle
Place of origin United States
Production history
Designer LeMAG Firearms LLC
Manufacturer Bushmaster/Hornady
Parent case .284 Winchester
Case type Rebated rim, straight wall
Bullet diameter .452 in (11.5 mm)
Neck diameter .4800 in (12.19 mm)[1]
Base diameter .5000 in (12.70 mm)[1]
Rim diameter .473 in (12.0 mm)[1]
Rim thickness .054 in (1.4 mm)[1]
Case length 1.700 in (43.2 mm)[1]
Overall length 2.260 in (57.4 mm)[1]
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)
Test barrel length: 20 in (508 mm)
Source(s): Hornady & Remington[2]
The .450 Bushmaster was developed for big game hunting with modern rifles.

The .450 Bushmaster 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 the standard M16s and AR-15s, using modified magazines and upper receiver assemblies.


The .450 Bushmaster is descended from the "Thumper" concept popularized by 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.[3]

Bushmaster requested[when?] the ammunition manufacturer Hornady to produce the .45 Professional cartridge for this project, but Hornady wanted to shorten the cartridge case to accommodate their 0.452" 250-grain pointed SST Flex-Tip bullet. Bushmaster and LeGendre approved the change from 1.771" to the now-standard 1.700", and a name change to ".450 Bushmaster".[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 is a high-pressure rifle case, thus making efficient use of heavy .452" bullets.[4] The cartridge is chambered in bolt action rifles by Ruger, AR-15 rifles, as well as an AR-15 pistol by Franklin Armory.[5]

Ballistically the round is very flat 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 3.4 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 five-round magazine, a 20-round AR-15 magazine body yields a nine-round magazine, and a 30-round body yields a 13-round magazine. Hornady and Remington both now manufacture ammunition for the rifle, and Starline manufactures empty brass for handloading.

See also[edit]


  1. ^ a b c d e f "CARTRIDGE and CHAMBER DRAWING - 450 BUSHMASTER" (PDF). SAAMI. p. 147. Archived (PDF) from the original on 2018-08-22. Retrieved 2018-08-22.
  2. ^ PREMIER® ACCUTIP™ 450 BUSHMASTER Remington Arms Company
  3. ^ Frank C. Barnes (5 October 2012). Cartridges of the World: A Complete Illustrated Reference for More Than 1,500 Cartridges. Gun Digest Books. pp. 97–. ISBN 1-4402-3059-5.
  4. ^ "45 Cal .452 250 gr FTX® (450 Bushmaster)". Hornady. Retrieved 2016-08-13.
  5. ^ Pridgen, D.K. "FRANKLIN ARMORY XO-26 .450 BUSHMASTER". Tactical-Life Magazine. Retrieved 26 Feb 2014.

External links[edit]