I couldn't ever get the concept of overkill.
Dead before it hits the dirt is a good thing in my books.
I doubt that 500gr soft did any hydrostatic shock type damage to the surrounding meat.
I say good kill.
No offense intended here, but...
Who gives a pinch of snot if he could have done the same thing with a 6.5 or even a bb gun for that matter?
The 470 did it just fine.

--Tinker