The 450 Bushmaster was designed by Tom LeGendre in 2008 to bring "big bore" performance into the AR-15 platform. Hornady has adopted it as a factory cartridge. Using a .452-inch bullet, it has a case length of 2.250-inches with a rebated rim. The 450 Bushmaster propels a 250-grain bullet at 2200 feet per second, yielding 2686 foot-pounds of energy. On game the 450 Bushmaster is similar in performance to the 45-70, thus well-suited for large game such as bear, moose, and elk in close cover. Numerous AR manufacturers offer 450 Bushmaster rifles and upper receivers, and Ruger has chambered it in their bolt action M77 Scout rifle.
