Man, you guys are bringing back some good memories.
I wanted to shoot a buff in the worst way with a 160-grain Ribtek, as that is what I have so much luck with on mule deer, bear, and big bull elk here in North America, but Bill Baker and Brad Kane said "No Way Mate, these are big brutes, you need a Grizzly!"
Well, they were right. I killed two dandy Melville Island bulls and had excellent penetration through heavy hide and thick bone with the 160-grain Grizzlies. I love my Ribteks, but have to admit, the Grizzlies were the ticket for Australian Buff.
I know you "could" kill a buff with other heads if all things are perfect, but I know you "can" kill a buff with Grizzlies even if you hit thick bone.
I was using a 75-pound Howard Hill longbow with Ipe (Brazilian Mahogany) arrows tipped with 160-grain Grizzlies. Total arrow weight was 860 grains.
The first bull I shot was laying down in a mud wallow, and from 15 yards I shot through the bottom of the sternum between his front legs, penetrating the heavy sternum bone (think thick, thick bone), driving up through the heart and lungs, and driving deep into the spine. The bull jumped up and locked eyes with me at 15 yards, and I thought that was it for me, but the effects of the arrow were already working on him, so I am here and he is not.
On the second bull, a large, heavily rutting herd bull, my arrow penetrated thick hide, centered a heavy rib, drove through the heart, and penetrated deeply into a heavy rib on the far side.
That's not bad for a 75-pound straight-limbed bamboo longbow, but in actuality, it's all due to the heavy arrow and narrow, long, ultra-sharp broadheads.
P.S. I was on the phone tonight with a friend in Australia, and with luck, will be returning for an Outback hunt in 2009. Backpack tents and a tarp, cooking over a campfire next to a fish-filled billabong for three weeks, and with luck, some large boars and bloody arrows. Can't wait mates!