For general hunting purposes, a 3-9x is ideal. the only instance I found more magnification to be needed was on my rifles I use for Ground Squirrel shooting, and I doubt you'll be using a .270 on those... 
No for ground Squirrels i will stick with my Marlin 39a .22 with the peep sight. That thing is amazing!
I think on my next Ground Squirrel trip I'll take my pellet guns. They all have scopes, though. When your eyes get older you learn to like optics more!

Seriously, though, a 3-9x is ideal for hunting. Keep it on the 3 to 4x setting for hunting. It's a lot easier to get on target quickly on lower magnification. (I found this out the hard way!)