Cooper Arms Model 21 Classic in 204 Ruger. The 204 Ruger in Classic configuration with oil-finish walnut represents Cooper's most practical modern varmint chambering in traditional dress. When the 204 Ruger was introduced in 2004, Cooper immediately chambered the Model 21 for it across multiple configurations. The Classic-grade version appeals to varmint hunters who appreciate fine wood as much as flat trajectories. Type: Rifle Action: Bolt-Action Caliber: 204 Ruger Capacity: 1 Year introduced: 2004, USA Weight: 56 oz Overall length: 41.5" Status: Active Intended use: varmint hunting