I’m usually an energy junkie and want to get as much energy out of a pellet gun as I can, but when hunting squirrels, I’m more concerned about getting a flat trajectory since I’m shooting past 30 yards. To do that, you have to find the right pellet for your particular gun.
I recommend ordering an assortment of pellets in the caliber of your air rifle. I tried 15 grain pellets, 16, 18, but most of all, I wanted the flatter shooting pellets. In the RWS rifle I was using in the 2nd episode of American Airgunner 2013, I was using a 14.66 grain pellet. It just so happens that particular pellet allowed me to shoot under a dime (in diameter) off my knee at 15 yards all day long. That put me about a 1/2 inch high at 30 and dead on at 40 yards. This was important since I was shooting at the relatively small vital areas of squirrels in the branches of trees.
Bottom line—Practice until you’ve reached the necessary marksmanship needed for the game you’re after. Shoot as many pellets out of your air rifle as you can and take the time to find the right pellet that fits your situation.