6.5X55 with 125gr Nosler Part to match a 270 Win, 140 gr to match a 7X57 & 160gr RN to exceed all the above.
I now use a 7mm08 - in a light Kimber Montana - a perfect solution out to 350 meters.
My other favourite was a Mod70 Win in 358 Win with 20 inch barrel & 225gr Sierras. It dropped deer in their tracks & you could eat to the hole! I still regret having sold the rifle.
-------------------- Always shoot through the target & not just at it.