I hunted in Az also with a 7 Mag. We rode horses/mules and shot from one mountain ridge to another at times. I used the 140g Nosler Ballistic tip, and NEVER lost a deer or pig. Having said that, I would go with the 140g Nosler Accubond, and any preceived problem would be solved. The load that I shot was as follows:
Rem brass
9 1/2
140g Nosler
64-65g of IMR 4350=3200fps in my Browning A bolt
or
66.5g of H-4350= 3300 in my browning A bolt
Both of these loads shoot less than 1/2" three shot groups.
Many times the deer will just stand there and look at you if they are beyond 400 with a wind that is not blowing to them. If you use a muzzle break, you can actually see your bullet impact, and hold for corrections on follow up shots. We shot some deer way out there, like two hills over using the above method. We actually had the time to get off the mule, screw on a bi pod, lay down on the ground and see if the deer had large enough mass to shoot. The main thing is to use a scope with enough power to where you will be able to see your bullet impacts. Your buddy being used as a spotter, usually does not give a specific enough
descripton of where the bullet hits. Plus, if he is using a 10x binoculars and you are using a 6-20x scope, you may be able to see a bullet impact on a rock, or dirt fly behind a bush that he can not see.
I don't think that you need a big heavy bullet in a 7 Mag for 500 yard shots or even 600 yard shots on DEER. You do need good bullet placement. There is no telling just what is going to happen with the Burger bullets (j-4 jackets) when they hit. The main thing is to go to Rio Salado and practice at 300,400, and 500 meters. Your deer hunting at 500 will be a piece of cake after the practice.
Good luck!