"I've practiced at 500 yards and I can make the shot. My range finder also adjusts for horizontal elevation distance to the target and my scope dials are matched to my particular bullet and load."
Did he practice in the same conditions as when he made the shot? There's your answer.
P
I hadn't realized there was a question...
But I'll put my oar in the water, as we all seem to be rowing in circles anyway. I don't have a problem with hunters shooting game at 500 yards, any more than I have a problem with folks doing so at 150 yards. I've seen plenty of folks who have no business doing either, and others who are dead nuts on at the same ranges. As you say, it comes down to how well you've trained.
I recall a hunting trip a few years back when I missed 4 animals out of 5 I shot at in the first 2 days of the hunt. This was with a very familiar and very accurate rifle and scope I had killed many heads of game with over about 8 years, btw. I was so confident in that rifle and it's pet load that any big game I'd selected inside of 400 yards always went down. I was puzzled by these misses, but as I didn't have an easy way to check the rifle out in the field, I switched to my backup rifle. I filled my remaining tags with no more misses.
When I went home, I found one of the scope ring screws was stripped, and 2 or 3 of the others were slightly loose. The rifle would barely hold minute-of-barn door at 100 yards. But I hadn't known this before the hunt because I only put 2-3 rounds down range at 100 yards to "check zero" before my hunt. If I'd followed my usual habit, and put 15-20 rounds on paper out to 400 yards prior to traveling to WY I'd have known about this problem before it became a problem. BTW, this pre-hunt Ritual has more to do with checking 'the nut behind the trigger' than any part of the rifle, IMHO; but as this case proved, rifles and scope mounts can and do get gremlins without warning, so it'/ smart to assume Murphy has been at work in your gunsafe every new hunting season.
In tactical circles, we often cite the mantra, "Train the way you expect to fight, for you will surely fight the way you have trained," and "If it ain't rainin', it ain't trainin'!" Same things apply to hunting. You have to train with your rifle from hunting positions, in hunting conditions, if you expect to succeed when you draw down at that trophy animal, whether it be at 150 yards or 1050 yards.
