RE: which scope for my 270 win
Yes, as the others have said forget about the see thru mounts. They are very weak and serve no real purpose.
I also agree with reddish about the Atec. I have had one for about 8 years or so and have ahd zero problems with it. It is plenty clear and bright for most hunters eyes.
I know it is hard to do but if you can save up a little more you can make a huge step up to a Burris Fulfield II. For just under $200 you can have a scope that compares with the Leupold VX-III, Pentax, Nikon Monarch, Weaver Grand slam. It would be worth the little extra waiting time and money.