Re: Deer hunting at 500 yards with a .243?
Personally, I would at least try one of the 105 grn bullets. I've always went off of 1000 ft.lbs energy and at least 1900'/sec (at the target) for big bodied deer. I am talking about deer that weight as much as 300 lbs live weight.
The 105 Hornady A-Max might stabilize in your gun, it might not, but it's worth a try if you really intend on some 500 yd shots. Most of the common 100 grn bullets don't have the BC to carry the energy like the 105 A-Max or Berger or Speer does. Regardless of the bullet used, I would definately only shoot if the deer was broadside and I'd put the bullet through the lungs/heart area. In other words, avoid quartering shots that would have to penetrate shoulder bones.
The model 7 I remember had a pretty short barrel. That being said, you might not be getting 2950+ velocities at the muzzle........which basically decreases the effective maximum range. Your altitude will also have an effect on the maximum distance. At Sea Level, the 105 A-Max at 2950 has 1000'lbs at 505 yds VS the 100 Sierra SBT (also shot at 2950) has 1000'lbs at only 395 yds, that's the BC helping you out.
In my honest opinion, I wouldn't attempt it with shooting 8" groups at 500 yds during practice. 5" groups maybe, but I would feel alot better about 3" groups. That way you know that any bullet you fire will land within a couple inches of where you're aiming so long as you call the wind right, and shot placement is crucial when running right at the effective limits of a cartridge.
Hope this helps.
Aim small = Miss small