There's tonnes of posts asking very similar questions.....
There aren't that many bolt guns with open sights anymore, the Ruger Gunsite does though, comes in 308 and has a 10 shot box mag.
Accuracy tests aren't that great though.
Tikka T3s are considered great guns and theres an open sight model but doesn't seem to come in many calibers.
Caliber wise I'd look at 308 and 260rem.
Both will get you out to 600yards, 260 is being used out to 1000 yards in competitions.