ive always used .22 over the years with great results and i no people who use 177 with great results,its what you get used to useing.i set my sights at 30 yards and i no thats good out to 40-45 yards,a well placed pellet in what ever caliber will do the job and if your new to air rifle shooting get in plenty of target practice at difrent ranges befor you go after rabbit,pigeon,etc