The .450 Bushmaster was developed by Tim LeGendre of LeMag Firearms and licensed to Bushmaster Firearms International and optimised for use on a standard AR-15 platform. It follows on from the writings of Jeff Cooper, a proponent of the Thumper effect, namely a large bore (greater than .44”) in a semi-auto platform that has enough power for a one-shot kill on larger game at ranges up to 250 yards.
