I would not shoot a deer at 500 yards with a 223, no matter what load. I have never shot a coyote past 300-350 yards with a 223, but it did get the job done out that far. If you want something to shoot deer size game out to 500, a 270 or 308 would both be fine.

308 has plenty of match quality ammo readily available, but I have never seen match ammo for 270. May not be a factor if you plan to reload, but there are a lot more match suited components for the 308.

A 223 will make it to 800 yards, but a 308 with quality handloads will make life a bit easier to make consistent hits that far out.

A 308 is about as much as an all around caliber as you will find in a factory rifle.