US Patent 10295319 Aerodynamic projectile

A projectile has a front portion and a cylindrical portion. The cylindrical portion comprises a cylindrical sidewall having an outer surface and an inner surface. The projectile also has a plurality of depressions in the cylindrical sidewall. The depressions have an outlet adjacent the second end, an inlet toward the first end and a neck area between the inlet and the outlet. A width of the inlet is smaller than a width of the outlet. The depressions at the neck area have a curved sidewall, but a generally straight sidewall between the neck area and the outlet. The surface of the depression extends at a ramp angle from the outer surface of the sidewall at the inlet of the depression toward the inner surface of the sidewall at the outlet.