55grain

55grain is a term commonly used in the context of firearms and ammunition, specifically referring to the weight of a projectile, or bullet, measured in grains. A grain is an old unit of mass, historically used for measuring grain, and is equivalent to approximately 0.0648 grams. Therefore, a 55-grain bullet weighs about 3.56 grams.

This specific bullet weight is most frequently associated with the 5.56x45mm NATO cartridge, which is the standard service rifle round for many NATO countries. The 5.56x45mm NATO, also known by its civilian designation .223 Remington, is used in rifles such as the M16, M4, and AR-15 platform. The 55-grain projectile is a very common and widely available option for this caliber.

Bullets of 55 grains are typically designed for general-purpose use, offering a balance of accuracy, terminal ballistics, and recoil. They are effective for target shooting, plinking, and as a standard hunting round for small to medium-sized game, depending on specific bullet construction and regulations. Factors like bullet construction (e.g., full metal jacket, soft point, hollow point) and the rifling twist rate of the barrel can influence the optimal performance of a 55-grain bullet. Other cartridges may also use 55-grain projectiles, but it is most strongly linked to the 5.56mm/.223 Remington family of rounds.