I don't think a brake on the Ruger would be that cost beneficial. A .308 is not a heavy recoiling cartridge, even in a light gun. If you are bothered that much by it, change loads to the Remington Managed Recoil load or imitate it with handloads. You should also invest in a PAST recoil shield of a good shooting coat with a good pad. You might want to have someone knowledgeable look at your posture on the bench. Spending a lot of time at a public range sending 50 or more rounds downrange through a rifle with a muzzle brake is going to make you a lot more enemies than friends as well as an intimate encounter with an audiologist.
I have a brake on a .340 WBY and a .338 Lapua...they are a necessary evil with those beasts.