In shooting straight up or straight down there is no lateral attraction to affect the course of the bullet, gravity acting only to aid or retard its speed, consequently the line of elevation will throw it off the target the full distance.
In shooting at any point in either the upper or lower quadrants, aim low; the lower as you approach either perpendicular.
The speed of a bullet diminishes as it travels, and as it requires much greater time to make the second than the first hundred yards, gravity has more time to depress it in that distance.
In bending backwards to shoot, remember that the rifle is inverted.
The flight of a bullet is not in a perfect curve; at first it travels almost straight, then curves gradually, then abruptly, till finally when it has lost its momentum, it drops perpendicularly, affected only by gravity.
If you are stationary and your target moves, aim ahead.
If you are in motion and your target is stationary aim behind, because your motion is given to the bullet.
If you and your target are both moving in the same direction at the same speed, near each other, aim at it, but if the distance be great, aim ahead, because your target keeps up its speed, while the momentum which you have given the bullet decreases as it travels.
The force of wind being irregular and capricious must be judged from personal observation and experience, but remember, that like gravity, it has more time to deflect a bullet during its second than during its first hundred yards flight.
Hold the gun firmly against your shoulder to prevent its kicking.