Lots of bad information on page one of this thread.
Bullets don't "rise" in terms of any effect that combats gravity, but you have to realize that you are shooting UPWARD. When you shoot a basketball jumpshot, you're throwing a ball upwards AND laterally, it goes up above the basket, and comes back down into it. A bullet is no different.
Gravity acts upon any body on earth, as soon as it's released from support, it'll get hit with 32.17fpsps downward acceleration. BUT, if you're sighted in at 100yrds, you've angled your barrel to shoot UPWARD just enough to overcome gravity for 100yrds.
Quite simply, if you don't shoot UPWARD relative to your line of sight, you'd never be able to shoot anything that wasn't below you, proportionately to the time of flight and the acceleration of gravity. That would mean if you were shooting 700yrds with a 308win, you'd have to be 16ft above the target, otherwise you'd never be able to hit it. For a 100yrd shot, your barrel is actually pointing about 2.5" above the target, for a 400yrd shot, that barrel has to point about 40" above the target. For a 1000yrd shot, you're actually pointing about 30ft above the target!
It always surprises me to see so many guys that do so much shooting that deny that their bullet is ever above their scope's line of sight.
Here's a link that you might find useful. Put in your bullet weight, scope height, ballistic coefficient, and muzzle velocity and you can see where your bullet SHOULD be impacting, or rather, how much hold over you'd need to account for.
Handloads.com Ballistic Calculator
For a 270win, you'll need to hold over to get 400yrds. I'd guess your load will have a Maximum Point Blank Range somewhere around 250-300yrds with a zero of 225-250yrds (MPBR is the farthest range where your "arch" of your shot is never above or below far enough of the line of sight (your crosshairs) such that it'll hit your desired target size with a dead on hold.