What is Impact of Temperature on .338 Winchester Magnum Ballistics?

Temperature’s Effect on Muzzle Velocity

Temperature plays a significant role in determining the muzzle velocity of a .338 Winchester Magnum rifle. According to ballistics data, a temperature change of 10°F (5.56°C) can result in a 20-25 ft/s (6.1-7.6 m/s) decrease in muzzle velocity. For example, at 70°F (21.1°C), the muzzle velocity of a 250-grain .338 Winchester Magnum bullet is around 2,950 ft/s (898 m/s), while at 30°F (-1.1°C), it drops to around 2,800 ft/s (853 m/s).

Impact on Kinetic Energy and Penetration

The decrease in muzzle velocity directly impacts the kinetic energy of the bullet, which in turn affects its penetration depth. A 20-25 ft/s (6.1-7.6 m/s) decrease in muzzle velocity results in a 10-15 ft·lb (13.6-20.4 J) decrease in kinetic energy. This reduction in kinetic energy can lead to a decrease in penetration depth, especially in thick-skinned game like moose. For instance, a 250-grain .338 Winchester Magnum bullet with a muzzle velocity of 2,800 ft/s (853 m/s) may penetrate around 18-20 inches (45.7-50.8 cm) of moose tissue, while the same bullet with a muzzle velocity of 2,950 ft/s (898 m/s) may penetrate around 22-24 inches (55.9-61 cm).

Hunting Strategies and Temperature Adjustments

When hunting with a .338 Winchester Magnum, it’s essential to factor in temperature changes and adjust your shooting technique accordingly. In colder temperatures, it’s recommended to aim slightly higher and use a slower, more deliberate trigger pull to compensate for the reduced muzzle velocity and kinetic energy. Conversely, in warmer temperatures, you can aim slightly lower and use a quicker trigger pull to take advantage of the increased muzzle velocity and kinetic energy.