Full Metal Jacket Boat Tail (FMJ-BT) Bullets

Full Metal Jacket ("FMJ") rounds are the most common bullet types loaded into a range, or training round. The core of the bullet is a pure lead core. It is encased in a copper jacket (in brass cased rounds, steel may have a Bi-Metal Jacket) with the bottom of the bullet showing the exposed lead core.

The "Boat Tail" description refers to the shape of the bullet. The rear of the bullet tapers inward, just like the hull of a boat. This shape gives the bullet a much higher ballistic coefficient. This shape also makes the bullet more aerodynamic, allowing a flatter trajectory due to the lessened affect wind has on the bullet.