|Grizzly Win Mag|
L.A.R. Grizzly Mark I in .45 Winchester Magnum with 6.5" barrel
|Place of origin||United States|
|Manufacturer||L.A.R. Manufacturing Inc|
|Length||267 mm (10.25 in) with 6.5 in barrel|
|Barrel length||5.4 in, 6.5 in, 8 in & 10 in|
|Action||Recoil-operated, closed bolt|
|Rate of fire||Semi-automatic|
|Muzzle velocity||426 m/s (1,400 ft/s) (.45 Win Mag 230gr bullet from 5.4 inch barrel)|
|Feed system||Detachable box magazine: 7 round|
|Sights||Fixed ramped blade front, fully adjustable rear.|
The Grizzly Win Mag pistols were conceived, invented, designed, engineered and developed in the 1980s by the sole inventor, Perry Arnett, who licensed his patented design for an interchangeable caliber automatic pistol (U.S. Patent #4,253,377) to 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).
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. Between 1983 and 1999, it was produced in 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 and Mark II models, offered in the mid 1980's were 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.
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 1911 pistol chambered for 45acp. 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.
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:
- Magazines - The magazine well is extended to accommodate the 45 WinMag cartridge, and the magazines are similarly deeper front to back. Magazines for 10mm and 45ACP contain a sheet metal insert that reduces the effective cartridge length capacity of the magazine. Magazines intended to chamber the 10mm round have modified feed lips and longitudinal grooves reducing the width of the feed channel. The overall magazine dimensions are identical to the standard 45WM magazine. LAR Grizzly pistols modified to accept standard 10mm magazines exist, but this was not a factory modification.
- Trigger - The Grizzly trigger bow is longer than the 1911
- Extractor - The extractor head is about 0.4 inches longer than the 1911
- Firing pin - longer than the 1911
- Barrel - Longer barrel hood than the 1911
- Michalowski, Kevin (27 October 2004). The Gun Digest Book of Guns for Personal Defense: Arms & Accessories for Self-Defense. Iola, Wisconsin: Gun Digest Books. p. 64. ISBN 0-87349-931-X.
Perry Arnett Patents at the USPTO related to the LAR Grizzly pistol: