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.
.450 Bushmaster (left), .223 Remington (right)
|Place of origin||United States|
|Designer||LeMAG Firearms LLC|
|Parent case||.284 Winchester|
|Case type||Rebated rim, straight wall|
|Bullet diameter||.452 in (11.5 mm)|
|Neck diameter||.4800 in (12.19 mm)|
|Base diameter||.5000 in (12.70 mm)|
|Rim diameter||.473 in (12.0 mm)|
|Rim thickness||.054 in (1.4 mm)|
|Case length||1.700 in (43.2 mm)|
|Overall length||2.260 in (57.4 mm)|
|Maximum pressure (SAAMI)||38,500 psi (265 MPa)|
|Test barrel length: 20 in (508 mm)|
Source(s): Hornady & Remington
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, and later built and delivered an AR-15 in .45 Professional to Cooper.
Bushmaster requested 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".
Loadings and ballistics
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. 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. Hornady, Remington and Federal now manufacture ammunition for the rifle, and Starline manufactures empty brass for handloading.
- "CARTRIDGE and CHAMBER DRAWING - 450 BUSHMASTER" (PDF). SAAMI. p. 147. Archived from the original (PDF) on 2018-08-22. Retrieved 2018-08-22.
- PREMIER® ACCUTIP™ 450 BUSHMASTER Remington Arms Company
- 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.
- "45 Cal .452 250 gr FTX® (450 Bushmaster)". Hornady. Archived from the original on 2017-07-10. Retrieved 2016-08-13.
- Pridgen, D.K. "FRANKLIN ARMORY XO-26 .450 BUSHMASTER". Tactical-Life Magazine. Retrieved 26 Feb 2014.