+1 Daryl & Ripp.

Whilst I have some experience (probably 5 weeks in total, hunting Alpine Game in NZ (Tahr & Chammy/Chamois), I came to a few conclusions.
The chambering and barrel length required, is dependant on animal size/weight (obviously), and the shooting distances, you might expect.
The other conclusion I worked out a long time ago, was there is no such thing as over kill!

Hope that helps

D'oh!
Homer