When culling roos I have to head-shoot them. The .242 imparts enough energy and gets there quickly, a (relatively) flat trajectory, so works nicely. I prefer my 6.5mm Creedmoor but it's too much for the job. Also my .308...Just too much.
I shoot my .243 out to past 1000m, but would not cull at that range. I shot a goat out there though, centre mass. My 65CM...Well past 1600m. I love that rifle system.