The Full Metal Jacket (FMJ) bullet: it sounds menacing, and in some contexts, it is. But what exactly is it? Simply put, an FMJ bullet is a projectile with a soft core (typically lead) encased in a harder metal jacket, usually made of copper or steel. This jacket isn't about armor-piercing in the way you might think, despite the name.
The primary purpose of the jacket is to improve feeding reliability in firearms. The harder metal prevents the softer lead from deforming as it's loaded and fired, ensuring a smoother and more consistent trajectory. This also reduces lead fouling in the barrel, extending the lifespan of the firearm.
While not specifically designed to penetrate body armor, the FMJ's shape and harder exterior make it more likely to pierce barriers than a soft-point bullet. However, its lethality stems primarily from its velocity and energy transfer upon impact, causing significant internal damage. Understanding the FMJ bullet means understanding its role: efficient feeding, reduced fouling, and consistent ballistics. It's a staple in many types of ammunition for a reason.
