Does Barrel Heat Affect Your Zero During Extended Shooting Sessions?

Understanding Thermal Expansion

Barrel heat is a common issue in long-range shooting, particularly during prolonged firing sessions. As the barrel temperature increases, the metal expands, causing the barrel to shift. This shift affects the rifle’s point of impact, resulting in a change to your zero. For every 10°F (5.6°C) increase in temperature, the barrel can expand by approximately 0.005 inches (0.127 mm) per foot (0.305 m) of length.

Measuring and Compensating for Barrel Heat

To compensate for barrel heat, it’s essential to monitor the temperature and adjust your aim accordingly. One method is to use a temperature gun to measure the barrel temperature. For every 10°F (5.6°C) increase, adjust your aim down by 1-2 MOA (minutes of angle) to compensate for the thermal expansion. Keep in mind that this is an estimate, and actual compensation may vary depending on the rifle’s barrel material and design.

Maintaining a Stable Zero

To maintain a stable zero, it’s crucial to follow a consistent cooling and shooting schedule. This involves firing a group of shots, allowing the barrel to cool for 10-15 minutes, and then adjusting your aim accordingly. Repeat this process throughout the shooting session to maintain a stable zero. Additionally, consider using a rifle with a heavy barrel or a muzzle brake, which can help to reduce barrel heat.