Developed to take advantage of the extremely accurate 6.5mm bullet the 6.5-300 is a 300 WBY case necked down from 30 caliber to 6.5mm. The result was the fastest 6.5mm cartridge on the market pushing a 140 gr bullet over 3400 fps. - CARTRIDGE SPECS - Bullet Diameter: .264 (6.5mm) - Common Reference: 6.5mm Caliber - Max Case Length: 2.825 - 129 Grain Hammer Custom