Are Aussie animals becoming like African animals, armour plated?

There have been hundreds of thousands of red deer and the heavy muscled and bone Himalayan tahr knocked over by 243s, 7mms, 308's etc. here in NZ. The 7x57 was one of the favourites for this job and the 7mm-08 has now assumed much of this mantle. Sure for longer range shooting the equivalent calibre magnums have found a place too.

You don't need premium bullets either, a good cup and core in the boiler room, high in the shoulder or brisket, or a Texas heart shot will anchor any cloven hoofed animal no matter what country it lives in.
A lost animal is just poor bullet placement, not an inadequate calibre or bullet.

I tried some 175gr Winchester factory loads in my 7x57 when I had one, only because I had a packet and wanted the shells for reloading, and I found them slow killers on red deer. Sierra or Hornady 140gr cup and cores were instant killers on any decent bullet placement with animals either dropping to the shot or moving only a few metres. I have always found velocities above 2600fps to produce infinitely better results than the slower slugs on deer and goats animals. Nothing wrong with a heavier bullet but it needs to be driven fast and open up.
Sierra 160gr Gamekings at 3000fps in my 7x61S&H rifle were dynamite on anything hit.

I now use a 7mm-08 with 140 to 150gr Sierra or Remington Corelock and would be perfectly comfortable plonking one into any of those Sambar pictured and be guaranteed an animal on the deck.

I always hark back to Jack O'Connors wife on safari in Africa where she took 17 head of plains game with 19 shots, the 2 extras were put into a big heart shot Kudu bull to prevent it running too far. The other 16 animals were one shot kills mostly all dropping to the shot. His wife used a 7x57 with Sierra 160gr bullets at 2700fps. What more do you need.

So yes of course the 7x57 will be perfect on Sambar, but will you?