Charles...
I think the 300 whisper will do exactly what you want IF (don't ya just hate those IF'S?)....
You don't expect much out of factory ammo! There is nothing wrong with CorBon Ammo it is just that you are limiting yourself and the guns capabilities based on one bullet/brass/powder combination. If you are lucky, your combination will put the corbons in to one tiny little group. But if it doesn't and your groups look more like "patterns" don't get discouraged. Just pick up some dies, bullets and brass and start playing with loads.
Remember you are building yourself a "custom" rifle and my experience is that if I want to be happy, really happy with a weapons performance I need to roll my own ammo. I have 2 whispers now and have had as many as 3 at one time and each had a little different idea as to what it like to wring out the most in accuracy and performance.
Get the corbon, break the barrel in properly and then go from there. The journey is 85% of the fun (and frustration)... Enjoy the journey!
DonT