Thread: Boat tails v.s. flat base projectiles

The theory is that a boat tail in certain bores may allow propellent gases to flow past the base, decreasing obturation of the projectile in the bore, and potentially allowing these gases to exit around the projectile at the muzzle unevenly, thus upsetting accuracy. By comparison, the flat surface area of the flat base, holds back more of the propellant gas, which pushes against this larger flat area, causing better obturation and sealing the gases behind the projectile.
Or something like that...