If you are considering shooting to 450 yards as you stated then a ballistic reticle or external turrets on your scope would be a must. It's not hard to get most rifles to shoot that distance but unless you can put the crosshair where you want the bullet to land at all ranges from 0-450 yards, you aren't shooting responsibly. Lots of chamberings will give you a 300 yard point blank range but after that it's an entirely new world, especially on some of the smaller sized game you've identified.
@sheephunterab
I've never used external turrets for any shooting, so I cannot say anything about that. Ballistic reticle I've used, but I haven't thought of adding that to this setup, but perhaps that would be a good addition. Thanks for bringing that up.
My longest measured shot was 342m using a 30-06 with a 3-9x40 duplex reticle. I do not take shot unless I'm confident with the shot and distance, know the drop and the distance. Most shots and animals I've taken are way below 200m so that would be a normal aim for the vitals shot.
The stated 400m would be the max in a pinch, but 300 would be the normal max. I consider myself a better hunter/stalker than shooter, so I prefer to come in closer, much closer, than the max numbers. Many times it is possible, but on occasions it is not, so whether I take the shot at max would be on the day, support, wind, recovery, how can I come closer etc.
I would however like to get the setup that would make the 400m possible if it comes to that. Then it would be, as you mentioned, up to me to be as prepared as I could possibly be to make a sensible and responsible shot.
Hope the above makes sense.
//Gus