In West TN there is the Tennessee Sports Foundation who has their range just South of Jackson. It says they have a 500 yard range now. Membership required.
The only other range over 200-300 yards anywhere near I know of is the range on the base at AEDC in Tullahoma, I know it goes to at least 1000 yards. I believe you have to be a member of the local gun club to gain access, although I'm not sure what the current status of that is or who to contact. I'd like to know that myself as I have some .50 I'd like to send down range.