This comparison examines two common types of 5.56x45mm ammunition used in the AR-15 platform and other firearms chambered for this cartridge. One type features a 55-grain full metal jacket (FMJ) projectile, a standard lead core bullet encased in a copper jacket. The other is a 62-grain projectile, often identified by a green-painted tip, indicating a penetrator core typically composed of steel or hardened lead beneath the jacket. These variations lead to different ballistic performances.
Understanding the performance characteristics of different ammunition types is crucial for responsible firearm ownership and effective use. The weight and construction of a bullet significantly influence its trajectory, velocity, and terminal performance. Choosing the appropriate ammunition for a specific purpose, whether it be target shooting, hunting, or self-defense, requires a knowledge of these factors. Historically, military requirements have driven the development of specific projectile types, such as those with enhanced penetration capabilities. This development influences the civilian market, offering shooters a wider range of options.