I have the Vortex Diamondback 3-9x40 on a muzzleloader. For the price I paid ($200), very good glass and build quality. I could use a smidge more eye relief but for a .308 you should be more than fine. In fact, I have a .308 Sako mounted with a Vortex Viper 2-7x32 and will likely switch scopes in the off season.