Elk trip a year from Nov...caliber?

[muzzlebrake]

Bullet choice may be more important than caliber. You don't want to use thin jacketed match grade bullets that may not penetrate or one dem girly man calibers that shoot too fast with tiny little bullets that deflect off the first leaf or twig. .308 will get er done with 165-168 bonded core bullets and reach out past 500 yds with ease and handle cross wind pretty good.

[Muddslinger]

Shot placement is key, pick a tough bullet. And keep it under 500 with .308.

[bustacap]

I would nix the 243 not nearly enough bullet. You mention you have a 308. I do also and have taken elk with it. If your into factory ammo I am a firm believer in Hornady 178 gr ELDX as that is the only bullet I now shoot in my 308. Its taken down the following all with one shot at the following ranges......
Bull-235 yds
Whitetails-100-325 yds
Stag - 225 yds
Tahr -225 yds
Wild goats -520 yds
Mule deer - 320 yds
Pigs -275 yds including one (threefer)

My point is this bullet is phenomenal in performance, it is devastating upon impact and just plain lets the air out of whatever it hits. The wound channel (internally) is quite unbelievable in the chaos it creates. Unless you make a really bad shot you won't have to look very far for your target animal after the shot. Good luck!

This is one of the bullets I use in the .308 and would be my first choice for elk.