Ruger Precision Rifle Hybrid 30 Cal Muzzle Brake 5/8" - 24One size suits 6. 5 Creedmoor and 308 Win model RPR's Reduces recoil by as much as 58% (depending on calibre and barrel length) contributing to improved accuracy over a longer string of fire. Brake locks into position using an easy to use external jam nut. Reduces noise and blast to the sides of the shooter. Installs quickly using a 11 16 box wrench or crescent wrench. Manufactured from alloy steel with a matte black finish. Threads: 5 8 24