.300 PRC Review: Everything You Need to Know Why do we need another .30-caliber magnum cartridge? March 12, 2019 By Tom Beckstrand Photos by Mark Fingar When I first learned Hornady was coming out with a long-action, .30-caliber magnum cartridge, the question that first came to mind was, Why? It was a good question since the .300 Winchester Magnum (WM) is America’s top-selling, long-action cartridge. Then there’s the .30 Nosler, another great design for a very-low-drag (VLD) bullet. And we can’t forget the .300 Norma Magnum (NM) and .300 Remington Ultra Magnum (RUM) for those who want as much powder behind a .30-caliber bullet as possible. Surely, those cover all the demands from a .30- caliber.