The question "How far will a .308 shoot flat?" is a common one among shooters, but it doesn't have a single, simple answer. The term "flat" is subjective and depends on your definition of acceptable bullet drop. This article will delve into the factors influencing .308 bullet trajectory, helping you understand its effective range and what constitutes a "flat" shot.
Understanding Bullet Drop and Trajectory
Bullet drop is the vertical distance a bullet falls below its initial trajectory due to gravity. A perfectly flat trajectory is impossible; gravity always acts on the projectile. However, at shorter ranges, the bullet's drop might be minimal enough to be considered "flat" for practical purposes. Several factors influence bullet drop:
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Bullet Weight: Heavier bullets generally have a lower ballistic coefficient (BC), meaning they are less affected by air resistance and will retain velocity longer, resulting in a flatter trajectory. Lighter bullets experience more air resistance, leading to greater drop at longer ranges.
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Muzzle Velocity: A higher muzzle velocity means the bullet travels faster, reducing the time it's subject to gravity, leading to a flatter trajectory at shorter ranges.
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Ballistic Coefficient (BC): This is a measure of a bullet's ability to overcome air resistance. A higher BC indicates less drop and drift.
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Air Density: Higher air density (colder, denser air) increases air resistance, leading to increased bullet drop. Conversely, thinner air allows for a flatter trajectory.
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Rifling Twist Rate: The rate of twist in your rifle barrel influences bullet stability. An appropriate twist rate ensures accurate flight; improper twist can cause instability and increased drop.
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Sight Height: The height of your sights above the bore affects the point of impact at various ranges.
The .308 Winchester: A Versatile Cartridge
The .308 Winchester is a popular cartridge known for its accuracy and relatively flat trajectory at moderate ranges. Its versatility stems from the wide array of bullet weights and designs available. However, even with the .308, bullet drop becomes significant beyond a certain point.
Factors Affecting .308 Flat Shooting Distance:
A typical .308 Winchester round fired from a standard length barrel will reach velocities upwards of 2700 ft/s. With a high-BC bullet, this translates to a relatively flat trajectory out to several hundred yards. However, consider the following:
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Acceptable Drop: What constitutes "flat" is subjective. For target shooting, a few inches of drop at 300 yards might be acceptable. For hunting, that same drop could be unacceptable.
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Wind: Wind significantly affects bullet trajectory, particularly at longer ranges. A strong crosswind can push the bullet off course, negating the benefits of a flat trajectory. Accurate shooting at longer ranges requires understanding and compensating for wind.
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Environmental Conditions: Temperature, humidity, and altitude can also affect bullet trajectory by altering air density.
Defining "Effective Range" for a .308
The effective range of a .308 is not simply the distance the bullet travels, but the range at which it maintains sufficient accuracy and energy to achieve its intended purpose (e.g., hitting a target accurately, taking down game).
Generally, a skilled shooter can maintain reasonable accuracy with a .308 out to 600-800 yards under ideal conditions. However, the bullet's energy will be diminished at longer ranges. Beyond that distance, factors like bullet drop, wind drift, and reduced energy significantly impact accuracy and effectiveness.
Case Study: Comparing Bullet Performance
Let's compare two common .308 bullets:
| Bullet Type | Weight (grains) | BC | Estimated Drop at 300 Yards (inches) |
|---|---|---|---|
| 150gr Match | 150 | 0.500 | ~15 |
| 175gr Match | 175 | 0.550 | ~10 |
This table demonstrates how a heavier, higher-BC bullet results in significantly less drop at the same distance.
Conclusion: Understanding the Nuances
While a .308 can achieve a relatively "flat" trajectory out to several hundred yards, the true effective range depends on many factors. Understanding these factors—bullet weight, BC, muzzle velocity, environmental conditions, and your skill as a shooter—is crucial for accurately predicting bullet drop and achieving your shooting goals. Remember, a skilled shooter can compensate for drop with proper holdover or scope adjustments. However, even the most skilled shooter will struggle to achieve consistent accuracy beyond the true effective range of the cartridge.