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.
.450 Bushmaster (left), .223 Remington (right)
The .450 Bushmaster was developed for big game hunting with modern rifles.
.450 Bushmaster single-stacks in magazines, unlike .223, which sits in two staggered columns
.450 Bushmaster cartridges and components
John Dean "Jeff" Cooper was a United States Marine, the creator of the "modern technique" of handgun shooting, and an expert on the use and history of small arms.
Jeff Cooper