I've had good luck out of the Hornady 143gr ELDX. One buck I did not recover but I blame it on poor shot placement on my part. I've shot 4 other deer with it this year, all at 500-600 (one at 815) and all dropped in their tracks. That being said, this is a smaller bullet with obviously much less velocity than your typical hunting rifles (270, 30-06, 7mm, etc.). I like it because it is an extremely fun target load that can be adapted to hunting, but it is at the lower limits of what I feel comfortable hunting with. And the ELDX is designed for expansion at long range. I don't think it does as well at expanding at long range as the same bullet does in larger calibers though.

People hate on it on ALDEER for a few reasons 1) They haven't shot it 2) It's popular in mainstream crowds 3) They haven't shot it

Here's a video from a couple weeks ago. I shot this doe (below) at 560 using the 143gr ELDX. Lighting didn't come from the sky to strike her down and she didn't evaporate, but the job got done more than humanely and probably better than Joe Blow with diddy's 30-06.

Ignore the stupid laughing, this is the second one at that distance we'd got that day on camera, so we were pretty excited.

https://www.youtube.com/watch?v=W2XIU0nlmRM

And I'll go ahead and address the long list of people who are about to come on here and say it is irresponsible to shoot deer this far. IT ABSOLUTELY IS... if you have not spent the required time (weeks at all different conditions, temps, etc.) to ensure you can make the shot. With that said, and to address your original question, go with ELDX if you are shooting within 500yds and I don't think you can go wrong. If you are not getting good results maybe try something with a slightly thinner jacket.

JB