Our friends at Wikipedia report that the standard .22 Long rifle used in varmint hunting has a slightly supersonic muzzle velocity of around 1125 ft/s(350 m/s) and a "normal" bullet weight of 2.5 to 2.6 grams (40 grains). So, your air rifle exceeds that velocity. I can attest, after many years of hunting small varmints on the ranch here in the western U.S., that, if the .22 works so well, your's will certainly do the trick. I'm somewhat surprised that an air rifle can reach that kind of velocity, however...