The Sierra BlitzKing .20 caliber (0.204") 39-grain PTBT (#1039) is a polymer-tipped varmint bullet designed for high velocity, accuracy, and rapid expansion. It features a thin, precision jacket and a boat-tail base that improves aerodynamics and long-range performance, along with a relatively high ballistic coefficient for reduced wind drift. Commonly used in cartridges like the .204 Ruger, it delivers flat trajectories and explosive impact, making it highly effective for small game and varmint hunting.