The mass of a projectile fired from a firearm is often expressed in grains. A grain is a unit of weight, specifically a unit of mass in the avoirdupois, troy, and apothecaries’ systems. For context, 7,000 grains equal one pound. As an example, a common 9mm bullet might weigh 115 grains, while a heavier .45 ACP bullet could weigh 230 grains.
The projectile’s weight significantly impacts its performance characteristics. Lighter projectiles generally exhibit higher velocities and flatter trajectories, resulting in less bullet drop over distance. Heavier projectiles, conversely, tend to retain energy more effectively and offer greater penetration, though they typically have lower velocities and more pronounced bullet drop. The choice of projectile weight is therefore a critical factor in optimizing ammunition for specific applications, ranging from target shooting to hunting and self-defense. Historically, the standardization of projectile weights was essential for developing consistent and predictable firearm performance.
