Pellets for seriously powerful air guns. Have you really got a powerful weapon? Then Exact Heavy is the right choice. Heavy. Stable. Accurate. It is being appraised for its low sensitivity for weather and windy conditions. Muzzle velocity is 215 m/s if the power of the airgun is set to 16J. The JSB Exact Beast pellet is one of the heaviest .177 caliber pellets sold today.