I agree on staying with 223. If you are going for a whole new caliber, I'd get something in 308 that will hunt/shoot other things than your 223's will... There are very good match grade loads out there for 223 that will shoot 0.5 MOA right out of the box while you build a good brass supply
In 223, I'd go Tikka T3 Varmint. Here's a discussion of same on another board:
http://www.tikkashooters.com/public_html/general-discussion/tikka-t3-varmint-223-accuracy/ It's generally perceived to be a sub 0.5 MOA rifle with the right ammo. Since you may handload, it may go down to 0.2" at 100 yds. That is, it's better than the shooter 95% of the time. A rifle that you can trust to be your companion in progressing in shooting up to competitive levels
The factory blurb:
http://www.tikka.fi/rifles/tikka-t3/t3-super-varmint
Notice that it's railed. So any scope you want in most any mount you want. Once you start finding really long ranges (400 yds +), you can get 10 and 20 MOA elevated mounts that bolt right on. That extends your useful scope adjustment capability quite a ways
IF you stay 223, I'd look at Leupold VX-R 4x12-40.
https://www.leupold.com/reticles/firedot-wind-plex/
It has a fire dot for close-in work. And can be turned off for range work. It has a wind-hold reticle. Although you can get other custom reticle's from Leupold for your chosen round with bullet drop. That means chrono'ing your best round and sending them the data. They will build a reticle for that round if you want. All it costs is money and time.
The 4x12 is a very useful all around scope. The 40mm bell means it can be fairly close to the bore so your point blank range will be good to prolly 250 yds once sighted.
But, if you will be working more at dawn and dusk, maybe a 4x12-50... This one has a bullet drop dial available so you dial-in you drop per your range and go from there.
Either way, the VX-R line is competitive with Nightforce and maybe has better glass/coatings for some situations... I'm not knocking Nightforce. I'm saying be careful with your budget. Buy a good scope. Go shoot. Learn what you want to change, THEN, go buy that scope and sell your starter. If it's a Leupold, you'll get 90% of your money back easy