The .177 caliber pneumatic air pistol features a single-action bolt design for easier cocking and loading, a rifled steel barrel for accuracy and an easy-pump forearm for variable pump power. Model 1377C Power Source: pump Caliber: .177 (4.5 mm) Max Velocity: up to 600 fps (182.9 m/s) Capacity: Single shot Length: 13.63" (34.62 cm) Weight: 2 lbs. (0.91 kg.) Material: Barrel: Rifled steel, Grip and Forearm: Synthetic