I have a remington 700 VTR in .308   I use the gun for deer season, and paper, my range goes to 300 yards (I know, not a meaningful distance for many on this forum but fairly unique for my area of NYS) I am looking for a cartridge that would be "very" flat shooting, and have a point blank range in the 300+ yard category.  I have been considering either a Cz, Tikka, Sako, or montana rifle company bolt gun in either .260 Rem, 6.5 x 55 or 6.5 x 284.  I've shot all of the calibers, though not a lot.  Does anyone have any experience with these guns in any of these calibers, shooting up to or beyond 300 yards and advice on which one would be the best overall flat shooting cartridge that would be good for deer as well.  
The rifle should be lightweight, and I accept the barrel life potential issue.  Are any of these that different than a 30-06 or 308 if we are talking 300 yards?  Just general commentary would be helpful before I invest in a gun.  
* I bought reloading equipment, so loading the gun won't be a problem.  

                                Thanks,
                                           Woody

If 300 is your max range then you aren't going to notice much difference between a .308/.30-06/.260/.270/etc. It's in the 300-400 yd range that you might start noticing, and even then it's not much until further out.

That said, in a lightweight rifle a smaller round is more pleasant to shoot. I have a Rem Seven in 7mm-08 and it is easy to carry and fairly gentle to shoot.

I'm in the same situation, I've narrowed my choices to the Kimber 84 Hunter, or the Sauer XT 100 Classic.  I just can't decide between the two.

At 300 yards max, one can stay in 308W and use a lighter bullet (like a 155 Scenar, Berger, TMK,...) push it out the tube at 2950 fps and end up with a 280 yard PBR.