As you might expect the most common topics on airgun forums are the features and foibles of the dozens and dozens of different models, but following closely behind the model discussions is the chatter about airgun ammunition or pellets. You may not expect that a.177 caliber pellet from Manufacturer A would perform wildly different from a.177 caliber pellet from Manufacturer B in the same airgun, but they do. To make it even more complicated Manufacturer B’s ammo may outperform Manufacturer A’s in a different air rifle or pistol.
We will discuss some of the different characteristics of airgun pellets and how you can use this information to your advantage when selecting a pellet for your air rifle or pistol.
A lighter pellet will leave the barrel of an airgun faster than a heavier pellet and it will also accelerate faster downrange. That means less time to target and a flatter trajectory because there is less time for gravity to work its magic. A heavier pellet will tend to have a less flat trajectory not because of its weight but because it spends more time to target providing gravity with more time to pull it towards the earth.
The second factor that most affects the flight of an airgun pellet is air resistance. Air resistance increases with the cube of speed. When you double the speed of a pellet moving downrange you increase its air resistance by eight times. Really light.177 caliber pellets lose energy due to air resistance so rapidly that after a 35 yd. or so it will be moving slower than a heavier pellet fired from the same gun. Air resistance is probably irrelevant for target shooting out to 10 m but it would play a big role in a hunting shot beyond that range. This is one of the reasons that you want to hunt with 303 British ammo the heaviest pellet your airgun can handle effectively.
In addition to the weight of the pellet air resistance will vary according to the shape of the pellet. Wadcutters are flat nose pellets used for paper target shooting. At the 10 m range the increase in air resistance is almost negligible but the same as with the effect of weight beyond 35 yd. the flat nose will start working like an air brake.
Medium weight round nose pellets offer the best compromise for both weight and shape for medium powered air rifles. For small caliber air rifles (.177 and.20) the best hunting ammo is a round nose hollowpoint. This pellet moves through the air as well as a regular round nose and mushrooms on impact significantly increasing the force of the shot.
The best advice about air rifle ammo is to try several different brands, several different shapes, and several different weights. What you read in the airgun forums may be true generally but may not work for your air rifle. If you are only an occasional shooter and still want the best accuracy and range then choose a premium pellet from the same manufacturer that made your gun. It is almost always best to avoid no-name bargains because there could be significant variability between pellets in the same package.