The Winchester StaBall HD Powder is a slow-burning spherical rifle powder for large-capacity magnum cartridges like the 6.5 PRC, 7mm Remington Magnum, and 300 PRC. It meters uniformly, which helps produce consistent charges and match-grade accuracy. The temperature-insensitive formula performs steadily in hot and cold weather, and copper fouling reducing additives help keep your barrel cleaner through longer sessions.