Grains - Bullet Weight - Definition

What are Grains?

Grains (gr) represent a unit of mass commonly used to measure the weight of bullets and gunpowder charges in the context of shooting and ballistics. One grain is equal to approximately 0.0648 grams or 1/7000th of a pound. Bullet weight, expressed in grains, is a critical factor influencing a projectile's external and terminal ballistics, as it affects trajectory, velocity, energy transfer, and penetration.

Understanding Grains and Bullet Weight

Bullet weight is typically specified in grains on ammunition packaging and technical specifications. The weight of a bullet can greatly impact its performance, as it interacts with other factors such as caliber, shape, and construction.

Key aspects of bullet weight and its influence on ballistics include:

  • Trajectory: Heavier bullets tend to have a more curved trajectory due to the influence of gravity, while lighter bullets may offer flatter trajectories and less bullet drop over distance.
  • Velocity: Lighter bullets often have higher muzzle velocities, as they require less energy to propel them. Heavier bullets, on the other hand, typically exhibit slower muzzle velocities but can retain velocity better over long distances.
  • Energy Transfer: Heavier bullets generally have greater kinetic energy, leading to increased energy transfer upon impact with the target. This can result in more significant tissue damage and better terminal performance in hunting applications.
  • Penetration: Heavier bullets tend to have better penetration due to their higher mass and sectional density, which can be advantageous when hunting larger or densely structured game animals.

Bullet Selection Based on Grain Weight

Understanding the role of grains and bullet weight is essential for selecting the most suitable ammunition for specific shooting applications:

  • Hunting: For hunting purposes, the choice of bullet weight depends on the size and structure of the game species. Heavier bullets with higher sectional density are often recommended for larger and tougher game, while lighter bullets with flatter trajectories might be more suitable for small to medium-sized game at longer distances.
  • Target Shooting: In target shooting or competition, lighter bullets with flatter trajectories and reduced recoil may be preferred for their improved accuracy and comfort over extended periods of shooting.
  • Self-Defense: For self-defense applications, a balance between bullet weight and velocity is crucial to ensure adequate penetration and energy transfer without over-penetration or excessive recoil.

Grains in Powder Charges

Grains are also used to measure the weight of gunpowder charges in handloading or reloading ammunition. The powder charge weight, in grains, is an essential factor affecting a cartridge's pressure, velocity, and overall performance.


  • Barsness, J. (2006). The Big Book of Ballistics. Skyhorse Publishing.
  • Litz, B. (2011). Applied Ballistics for Long Range Shooting. Applied Ballistics LLC.
  • Brezny, L. (2013). Gun Digest Guide to Modern Shotgunning. Gun Digest Books.
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