243 or 308?

Clemmer, preceding comments are on target, long range shooting takes practice. My opinion is the 308. There's a reason it has been a preferred sniper rifle for a very long time. Heavier .308 BT bullets have excellent ballistic coefficients which become very important past 400 yds when compensating for wind drift and elevation. The comments about a good scope are very correct. Try several options, test the adjustments, cross-hair clarity at high power, etc. Most of all get trigger time on the rifle to know how it feels and shoots with different loads, you'll settle into your favorites soon. Have fun

Thanks everyone, I just picked up the night train in 308 and I love it. I can't wait to see what I'm capable of doing with it

There is a very legitimate and intense debate regarding the ethics of HUNTING at ranges of 600-800 yards. This is not the forum to get into that debate other than to reinforce the preceeding good advice that while shooting at extreme ranges can be done it take a major commitment of equipment, shooting education, experience and lots of ammo to do so. WHether or not it should be done on live targets is an entirely seperate discussion. For banging at paper or steel targets...fine...go for it.
FWIW, I have been a rifle hunter for 40+ years and the longest shot I have ever attempted was on an antelope at 400 yards and I had some reservations even at that yardage.

Good luck and let us know how it goes...

Being nosey

Just curious, if you don't mind, how much $ otd for gun, tax, background check? I'd bet you could have found a good conditioned 1960-80's Rem mdl 700, or win mdl 70 (A MUCH BETTER GUN) likely for less $ if you hadn't been impulsive. Act in haste repent in leisure. As most of us have or are in the process of learning, buy quality ONCE and enjoy it for life, instead of lesser quality over and over. Wanna know, how WE KNOW? been there, done that. Good luck and let us know when you hit that x ring at 800.

Thanks everyone