Quick Answer
Temperature affects the performance of a .325 WSM by altering the ballistic coefficient of the bullet, which in turn affects its trajectory and accuracy. In cold temperatures, the bullet's expansion slows, increasing its ballistic coefficient, while in hot temperatures, the bullet expands more, decreasing its coefficient. This affects the bullet's performance and accuracy at longer ranges.
Bullet Expansion and Temperature
The .325 WSM is a popular caliber for elk hunting due to its flat trajectory and high kinetic energy. However, bullet expansion and temperature can significantly impact its performance. In cold temperatures below 40°F (4°C), the bullet expands less, resulting in a higher ballistic coefficient and improved accuracy at longer ranges. For example, a .325 WSM 180-grain Nosler Partition bullet expands approximately 0.03 inches at 40°F (4°C) compared to 0.05 inches at 70°F (21°C).
Load Selection and Temperature
When hunting in cold temperatures, it’s essential to select a load that is designed for cold temperatures. For the .325 WSM, a load with a higher powder charge and a bullet with a higher ballistic coefficient will perform better in cold temperatures. For example, a load with 90 grains of H1000 powder and a 180-grain Nosler Partition bullet will perform better at 40°F (4°C) compared to a load with 85 grains of H1000 powder and a 180-grain Sierra GameKing bullet.
Range Estimation and Temperature
When estimating range, it’s essential to consider the temperature and its impact on the bullet’s trajectory. At longer ranges, the temperature can have a significant impact on the bullet’s drop and wind deflection. To compensate for temperature, hunters can use a ballistic calculator or consult a ballistic chart that takes into account the temperature and humidity. For example, at 1,000 yards, a .325 WSM 180-grain Nosler Partition bullet will drop approximately 10 inches more at 70°F (21°C) compared to 40°F (4°C).
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