Question: what is the difference in the grain of a bullet?
Answer: The term grains refers to the projectile's mass or weight. A grain is a very small unit of measurement where there are 437.5 grains in an ounce. Therefore, if you were to purchase a box of . 223 Brown Bear 55 Grain FMJ, the 55 refers to the mass of the bullet itself, not the entire cartridge—just the projectile.