ANATOMY OF THE BOAT-TAILS IN RIFLE PROJECTILES BOAT-TAILS:           A properly designed boat-tail can increase the BC of a bullet by decreasing base drag. There is a low-pressure area at the base of the bullet as it travels thru the air at high speed. That low pressure region (vacuum) behind the bullet is applied to the area on the base of the bullet and results in base drag. The goal of a boat tail is to reduce the effective base area to which this vacuum applies.           Tapering the back of a bullet allows the air to flow along the boat-tail before separating off the reduced diameter base. The boat-tail produces a smaller base area for the low pressure to act on, thereby reducing base drag.           There are some limitations to what you can do with boat-tails. One common instinct is to make the boat-tail longer, the idea bein...