Gunwerks patent-pending design allows a user to remove the stock and barrel with just a T25 wrench, and assemble it again with a new barrel and a new cartridge - all in minutes, without any concerns for part fitment or headspace safety concerns. Gunwerks control the fit of their proprietary changeable bolt head and barrel extension with precision CNC machining to allow you the simplest installation possible. 20 " barrels 300 PRC or 65 PRC Mfg: Gunwerks