Cooper Arms Model 21 Montana Varminter in 223 Remington. The Montana Varminter is a Cooper-exclusive stock configuration featuring a broader forend and higher comb designed specifically for shooting from improvised field rests and shooting sticks common in western prairie dog country. The 223 Rem Montana Varminter is Cooper's most field-practical varmint configuration — built for the way western hunters actually hunt rather than for the benchrest. Type: Rifle Action: Bolt-Action Caliber: 223 Remington Capacity: 1 Year introduced: 1993, USA Weight: 62 oz Overall length: 43" Status: Active Intended use: varmint hunting