You need to put a good scope on it. It also depends on the type of bullets you use.

I've got a 30.06 that shoots a group of about 1" at 100 yards benched with Remington Core Lokt 165 grain. Benched is a lot different than standing/kneeling - so it's important to practice. That bullet will kill both of what you want. The kill zone on a deer is about 6". If you hit the bottom, middle, top of that zone it doesn't matter, it's dead.

You'll want to set up your gun so that the bullet's arc will not go above 3" of where your scope's reticle is centered, and know when it will drop 3" below where you're centered. That way, you just center on your kill zone and bam. My 30.06 is zeroed in at 215 yards - it's about 2" high at 100 yards (still in the kill zone) and it falls 3" and out of that kill zone at about 260 yards. That's as far as you'd want to shoot a Rem Core Lokt anyways.

There is a wide variety of bullets out there that have different abilities, and some will have good lethal penetration much farther than that... but on a close shot some of them risk passing out the other side without expanding enough to kill fast.

I personally would not likely shoot over 250 yards anyways... unless things were perfect.

Now other people are probably going to disagree with everything I've said... but those are my opinions.

Thanks for the advice. I'd hate to overreach myself and end up with a wounded animal (and the tracking that goes with it). Hope to share success stories in the future.