Back in the 70's I shot 3 position and prone matches with a bunch of WW11 vets. Most of them lived on Vancouver Island during the summer & fall hunting season, but had lodging on the mainland for the winter and spring-time. That is where we shot - at the Barnet Range, on the Burnaby highway, just outside Port Moody, B.C.
Where was I going with this? Well, most of those "old guys" shot .222 Sako A1's (like mine) for 3 po and prone competition. Th eodd guy used a L46 sporter in .222. They also used them with 50gr. Spire Points or 50gr. Speer Spitzers for the island deer in the fall. One guy used the 70gr. Speer, but some said it didn't shoot well in their 14" twists. Their "cabins" bordered crown land and they'd just sit on the porch, the table was a bench rest & POW! The freezer was filled quite easily.
The coastal "black tails" are not large deer like the mainland muleys.

A .222 should make a credible goat rifle for Australia, no?