Engineering360: "The Race to Deploy Devastating Hypersonic Railguns Heats Up"

Seems to me that the projectile should be BICONICAL to minimize drag induced by the vortex created by the blunt rear of the projectile...

Hypersonic aerodynamics are a bit different from the subsonic regime. Shock wave management and the area rule dominate design. Another consideration is the acceleration force of the launch and the necessary pressure on the back of the projectile. It would not do to have it spall apart in the launcher.