Technically yes, the thread and caliber will match. But the manufacturer does not recommend installation on barrels shorter than 14.5". For this kind of application, see the Precision Armament EFAB.
Yes, the 5/8-24 Hypertap is compatible with the Ruger American Ranch Gen 2 .308 Winchester Rifle.
The outside diameter (OD) of the slim body Hypertap is .90". The OD of the standard body Hypertap is 1.09".
Yes, this brake will work on a 6.5 Creedmoor. There are specific Hypertaps made for 6.5mm cartridges though available as well.
Yes, the Precision Armament Hypertap Muzzle Brake will be compatible with your Ballistic Advantage .308 barrel.
The Precision Armament Hypertap Muzzle Brakes, .308/7.62 will work with a 6.5 Grendel that is threaded for 5/8x24.
the OD is 1.09".
please follow the provided link for more information on the .308 option:
https://www.opticsplanet.com/precision-armament-hypertap-muzzle-brake.html?_iv_parent-caliber=dot-308-winchester
As long as the thread on the person's firearm is 5.8-24 than this brake will work for a .300 blackout and a 300 Win Mag rifle as those projectiles both have a diameter of .308.
Please follow the provided link for the 7.62/.308 option.