If there was one rifle suitable for all types of hunting, gun safes would be much emptier than they are now. Each caliber has been developed to fill a certain role, offering a combination of powder and lead tailored to excel at a particular task. You wouldn’t take a dangerous game rifle on a fox hunt and you might not come home if you took your varmint gun on safari. The same goes for air rifles. Just like with rim- and centerfire rifles, you have to match the caliber to the size of your quarry. But if you are pursuing small game such as squirrels and rabbits, you would be well-served with a .22 caliber rifle capable of producing at least 12 foot-pounds of energy at the muzzle.