Measure the distance of your shot to define the variable of R (range) for the motion equation.
Find the speed of velocity at which the bullet leaves the barrel of the weapon. Use this figure to define the variable of V in the motion equation.
Use the following motion equation to calculate the angle of the shot: first, take the force of gravity (-9.8 meters per second squared), multiply it by the range of the shot, then divide the outcome by the initial velocity of the bullet squared. Multiply the answer by the inverse sine function.
Divide this final number by 2 to calculate the angle of the shot.