LAR Grizzly Win Mag

The Grizzly Win Mag pistols were conceived, invented, designed, engineered and developed in the 1980s by the sole inventor, Perry Arnett, who licensed his patent for an interchangeable caliber semi-automatic pistol to L.A.R. Manufacturing Inc. Perry Arnett's designs were initially flawed and were improved upon by Heinz Augat (former owner and founder of L.A.R. Manufacturing Inc.). The L.A.R. Grizzly was the most powerful semi-automatic pistol ever commercially produced (the Mark V was chambered in .50 AE to compete with the IMI Desert Eagle).
Background.
The LAR Grizzly pistol was a modified Colt M1911 style pistol with oversize components designed to handle larger, more powerful cartridges than could be used in the standard size 1911 pistol. The original prototype built by Perry Arnett was made from two Colt 1911 frames and slides cut and welded to accommodate the 45WM round, with two steel doubler plates welded to the slide flats to retard the action and increase strength.
Between 1983 and 1999, approximately 15,000 guns were produced in four versions capable of firing 6 different cartridges. All guns were hand fitted and capable of high accuracy.
The Grizzly is an oversize of the Colt M1911 design, and most parts are interchangeable with those of the standard size pistols of other manufacturers. The Mark I model, offered in the mid 1980s was developed to fire the powerful .45 Winchester Magnum round. At various times, conversion kits were sold allowing the pistol to fire other rounds, including .45 ACP, 10 mm Auto, and .357 Magnum. Later, the Mark IV model was designed specifically to handle high pressure .44 Magnum loads, and the Mark V was designed to chamber the still more potent .50 AE. The 357/45 Grizzly WinMag .357-.45 GWM was a powerful wildcat round designed for the LAR Grizzly pistol.
The standard Grizzly models had a 5.5" slide, most often seen fitted with a 6.5" barrel which extends one inch beyond the slide, and less commonly with a 5.5" barrel in combination with a factory fitted bushing style recoil compensator. Special models with 8" and 10" barrels for hunting and silhouette competition were also produced (in small quantities).
A Grizzly caliber conversion kit typically included a barrel, a magazine, an ejector, an extractor, a barrel bushing, and a recoil spring. Some also included a bushing type recoil compensator and a wrench for use with the compensator.
Operation.
The standard recoil spring used in the Mark I and II pistols chambered for the .45 Winchester Magnum has a 27lb rating, compared to the 16lb rating for a standard M1911 pistol chambered for .45 ACP. The heavy spring, combined with the greater inertia of the massive slide, results in a manageable recoil impulse without resorting to the gas operation of the Desert Eagle and Wildey designs. The absence of any small, easily fouled gas ports makes the LAR Grizzly capable of firing cast lead bullets reliably.
The Grizzly utilises a standard 1911 Commander length barrel bushing to accommodate the greater excursion of the slide and associated swing of the barrel required to feed and eject the long .45 WM cartridge. In spite of this, the bushing tends to develop skirt cracks after hundreds of rounds of full-power loads. As the bushing skirt fails, the point of impact will drift downward.
The Grizzly pistol design does not utilize the double-tapered barrel tenon accuracy enhancement patented by Perry Arnett.
Non-standard parts.
Most of the small parts used in the Grizzly Mark I pistol are standard parts per the 1911 ordnance drawings. Some parts however are not interchangeable due to the increased front to rear depth of the magazine well:
External links.
Perry Arnett Patents at the USPTO related to the LAR Grizzly pistol: