It' s hard to use a scope for both varmints and deer on that particular caliber.

Like what diyj98 said, a 6mm isn' t the perfect caliber for bigger game at long distance, but is alright for close range(200 yards or so, maybe a little more if you reload). For varmints, a high power variable scope would be good. For deer, I wouldn' t go over 12 power, like what stubble said. But, all I have ever used was a 3-9x40 Leupold on my rifles for deer. You can kill deer with that caliber at a good distance, but it' s not the perfect caliber for it. I think you picked the right caliber if you are useing it for both varmints and deer. A little more powerful than a .243, and a flat shooter at long distances.