Designed to be bored out for designated caliber 6mm - 30 Cal
Ports are indexed to the side for prone shooting with forward facing vent holes direct blast away from the shooter
.875 OD and 5/8-24 TPI
PLEASE NOTE: These brakes are not pre-bored and need to be drilled to your specific caliber before installing and firing. Installation should be completed by a competent gunsmith.