OPINION | ARKANSAS SPORTSMAN: Deflection important to understand

Bullet deflection is probably the most misrepresented topic in shooting.

Deflection is a bullet's horizontal deviation from point of aim. We know that a bullet drops during its path to a target. The greater the distance, the farther and faster it drops. The faster it travels, the less it drops because speed reduces its time aloft and thus reduces its exposure to gravity.

Deflection describes lateral movement that occurs because of wind. The stronger the wind, the greater its potential for moving a bullet to the side of a rifle's point of aim.

A recent article in a national magazine illustrated this phenomenon with a graphic that represented a bullet's path deviation as a curve, or an arc that would eventually result in a 90-degree course change.

That is not how it works.

A bullet travels through air. Air usually moves. If air is moving, it will carry anything traveling through it a commensurate distance in the direction it is moving.

In this sense, a bullet in air is similar to a boat in water. On a day when the Arkansas River has no current, start at Point A on the south bank and aim the bow at a fixed point B on the north bank. On a perfectly straight heading, you will arrive fairly close to point Point B.

Keeping a straight heading on a day when current is strong, you will arrive at the north bank far downstream from Point B. That is deflection.

You can reduce the distance you arrive downstream from Point B by going faster. Assuming you performed both exercises at full throttle with a 50-horsepower motor, the only way you can go faster is with a more powerful motor.

Translating that analogy to ballistics, increasing horsepower is equivalent to increasing the powder charge behind a 150-grain, .30-caliber bullet.

You can also reduce deflection crossing the river by using a more hydrodynamic hull, which will reduce resistance and increase speed. An example would be switching from a flatbottom boat with a wide bow to a more cylindrical, pointed hull that has less contact with the water on plane.

That illustrates the difference between a blunt-nose bullet with a low ballistic coefficient to a sleek, streamlined bullet with a high ballistic coefficient. The blunt bullet is more vulnerable to wind deflection because it plows through the air instead of slicing through it.

If you graph your boat ride across the river, you'll notice that your deviation is not uniform. The rate of deflection spikes where the current is strongest, and that spike determines the rate of deflection, or sidelong motion. The rate of deflection decreases when the boat encounters weaker current. If the current is strongest against the north bank, the rate of deflection will be greatest closer to Point B.

If the current is strongest on the south bank, the greatest amount of deflection will occur at the beginning of the trip.

We often see this phenomenon when shooting. The wind might be howling at the muzzle, but it might be practically slack at the target, or vice-versa. Either way, the rate of deflection is greatest where the wind is strongest.

The angle at which wind contacts a flying bullet affects the rate of deflection, as well. Wind contacting a bullet at a 90-degree angle produces the greatest amount of deflection.

If you graph the path of a boat or a bullet, it will not curve, but it won't be straight, either. It will be more of a fade. A more aerodynamic bullet traveling faster will fade less.

The weight of the bullet factors into this equation, as well. A 165- or 180-grain, .30-cal. bullet is substantially slower than a 150-gr. bullet in the same caliber fired from an identical case, but it is also longer. Depending on the design, the longer bullet might be more aerodynamic than the shorter bullet.

Returning to the boat analogy, a comparative example is the Iowa class battleship versus the South Dakota class battleship. The Iowas weigh 61,000 tons at full load, compared to 45,000 tons for the South Dakotas. The Iowas are almost 200 feet longer, but both are 108 feet at the beam. The Iowas were 6 knots faster, and they operated at top speed more efficiently than the short, squat South Dakotas.

Deflection is an inescapable element of shooting at long ranges. It can determine the difference between killing, wounding or missing a game animal, but it's a lot more complicated than a neat, uniform arc on paper.

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