The .22 caliber pellet grew out of the .22 rimfire, which, at the start of the 20th century, was the choice for most small shooting jobs like pest elimination. But a .22 caliber pellet is no longer the same diameter as a .22 rimfire bullet, nor will a rimfire barrel work well for pellets. The rimfire barrel is sized 0.222- to 0.223-inch across the grooves, while the airgun barrel is sized 0.217- to 0.218-inch. The .22 caliber pellet is definitely the choice of the hunter and pest eliminator. It both hits harder and also transmits more of its energy to the target than the smaller .177. But pellets are not centerfire bullets. They don’t travel 3,000 f.p.s. and faster. At even a top speed of 1,200 f.p.s., a pellet is going too slow to have a similar hydraulic shock effect on game. So a fast pellet is of no advantage to a hunter unless it also carries a large amount of energy that it can successfully transfer to the animal.
That’s why the .22 is the king of the hunting calibers. As far as general shooting goes, the .22 caliber is just fine. The pellets do cost more than .177s and the velocities of the guns are usually slower, but a good shot will have no problem with a .22. It is the second most popular airgun caliber.