Does bullet expansion vary significantly between 150gr and 165gr?

Bullet Dynamics

Bullet expansion is primarily determined by the bullet’s velocity at impact, not its weight. The 308 Winchester’s relatively low muzzle velocity, typically ranging from 2600 to 2800 ft/s, limits the kinetic energy transfer to the target, which in turn affects expansion. A 150gr bullet at 2600 ft/s might achieve 15% expansion, while a 165gr bullet at the same velocity might achieve 12-14% expansion, resulting in a relatively small difference in expansion between the two weights.

Expansion Mechanisms

The expansion process is influenced by the bullet’s material, design, and the target’s characteristics. Jacketed hollow-point bullets, like the 150gr and 165gr variants, are designed to expand through a combination of material deformation and the creation of a cavity. As the bullet encounters the target, it begins to deform, and the jacket material begins to stretch and eventually fails, allowing the core to expand and create a larger wound channel. The design of the bullet, including the ratio of jacket to core, the shape of the cavity, and the hardness of the materials, all play a crucial role in determining the extent of expansion.

Practical Implications

In practical terms, the differences in expansion between 150gr and 165gr bullets may not significantly impact the effectiveness of the bullet in a hunting context. Both weights are designed to deliver a clean kill, and the choice between the two often comes down to other factors, such as bullet availability, cost, and personal preference. However, it is essential to consider the specific hunting scenario, including the target animal, shot distance, and angle, when selecting a bullet weight.