There are many different types of air rifle pellets on the market, and the heaviest 177 air rifle pellet will vary depending on the specific type of pellet you are looking for. The heaviest pellets tend to be made from materials like lead or steel, and they can weigh anywhere from 7.9 to 18 grains. The majority of pellets in this weight range are designed for hunting or target shooting applications, and they can offer significant power and accuracy benefits over lighter pellets. If you are looking for the heaviest 177 air rifle pellet available, make sure to check out some of the options from companies like JSB Match Diabolo or Crosman Pointed Hunting Pellets.