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Determining Energy or Foot/Pounds- Finding the Magic Pellet
How do you find out how much energy or foot-pounds a pellet has? First of all, it is almost imperative that you have a devise called a shooting Chronograph. Commonly called a “Chrony” it has the ability to measure the velocity of a given projectile. Multiply the weight of the pellet by the velocity of the pellet by the velocity of the pellet again and divide by the constant of 450249 and result is foot-pounds of energy or power. For example, an 8-grain pellet traveling 800 feet per second equals 11.37 foot-pounds of energy. Multiply 8 x 800 x 800 and divide by 450249 gives the result of 11.37fpe.
The easiest way to do this is have a gun vise that is locked down so that it cannot move. Then attach your air gun to the gun vise so that it also cannot move. In the case of a springer, attach it upside down. Set up a target at a distance of ten meters and fire your air gun so that it hits the center of the target. The target can be a simple sheet of 8.5″ x 11″ copy paper. Move the target, not the gun until you are hitting the center of your copy paper. Lock down what ever it is that is holding your target so that the target cannot move.
Set up your Chrony in front of the barrel according to the instructions, turn it on and begin shooting six to ten of your lightest pellet for your first sequence. Record the weight of the pellet and the chrony readings. Measure the distance between the two farthest holes on your target to determine the size of the group.
Tear off the old target and replace or staple on with a new target, shoot a string of the next heaviest pellet and be sure you put in a new powerlet if your air gun is a CO2 (this may seem wasteful but you have to compare apples with apples) and re-fill if your air gun is a PCP. Repeat this process until you find the magic pellet that is going through the same hole shot after shot. Then repeat the process and use yet a heavier pellet and you should find that the groups are beginning to become larger again.