Hauptjager,

The cannelure is a knurled or sometimes machined groove into the bullet jacket. Its main purpose is for crimping the bullet into a loaded round.

If time was short and I was after thin-skinned game as you say; and if the range may be out a ways; I'd probably opt for a 270gr factory load. The Winchester power Point has worked alright for me but it opens quick up close. Hornady also makes a factory 270gr load with their Spire point which should be fine as well. This bullet opens quickly as well.
Although I haven't tried them, Federal has a premium load called "Vital Shok" (I believe) that is loaded with a Nosler 260 grain Accrabond. While I haven't shot these, I would trust the bullet from the comments of friends that have.

BigRx