Does Seating Depth Influence Accuracy with Reloaded Ammo?

The Importance of Bullet Engagement

When reloading ammo, the seating depth of the bullet is a critical parameter that can significantly impact accuracy. In cartridges with a long throat or freebore, the bullet is more sensitive to the seating depth due to the increased distance between the bullet and the rifling. A seating depth that is too long or too short can cause the bullet to engage with the rifling at an angle, leading to instability and reduced accuracy.

For example, in the .308 Winchester, a seating depth of 0.050-0.070 inches is considered optimal for most bullet weights and types. However, for cartridges with a long throat, such as the .30-06 Springfield, a seating depth of 0.070-0.090 inches may be more suitable. It’s essential to consult the manufacturer’s recommendations and experiment with different seating depths to find the optimal value for your specific rifle and ammunition.

Measuring and Adjusting Seating Depth

To measure and adjust the seating depth, you’ll need a dial caliper or a depth micrometer. Start by measuring the length of the case and the bullet, then calculate the optimal seating depth based on the manufacturer’s recommendations. Next, use a reloading die or a precision seating die to adjust the seating depth of the bullet. It’s crucial to make small adjustments (0.001-0.005 inches) and measure the results to avoid over- or under-seating the bullet.

When making adjustments, pay close attention to the bullet’s engagement with the rifling and the resulting accuracy. You may need to experiment with different seating depths and bullet weights to find the optimal combination for your rifle and ammunition. With patience and attention to detail, you can achieve improved accuracy and consistency with your reloaded ammo.