The 45 Winchester Magnum was introduced in 1979 but was technically not a new design. It is dimensionally and balistically the same as the 45 NAACO that was developed for the Canadian military in 1959, but not adopted. It is a lengthened version of the 45 ACP, but with a much stronger base. It was chambered in the L.A.R Manufacturing (Larisch, Augat and Robinson, the founders of the company) Grizzly Mk.1, which was a scaled up version of the 1911 to handle the extra pressures. (Erlmeier, Brandt Ref. 440)