The Forster .300 Blackout GO Gauge provides gunsmiths with the most reliable method to test rifle chamber length and ensure proper headspace. Made from precision steel construction with exacting manufacturing standards for accurate chamber testing and shooter safety.Forster .300 Blackout GO Headspace GaugePrecision steel construction for durability and accuracyTests chamber compliance with S.A.A.M.I. specificationsEssential safety tool for preventing dangerous excessive headspaceProfessional-grade gunsmithing equipmentIf a rifle closes on this GO gauge the chamber will accept any ammunition made within S.A.A.M.I. industry standard specifications. Proper headspace gauging prevents dangerous brass rupture and ensures optimal accuracy and safety for .300 Blackout rifles.