Skip AI,
The Edge is just the 300 RUM necked up to 338 with no other changes. Shawn changed the name so there was much less chance that someone would see the 338-300 RUM and mistakenly chamber a 338 RUM and shoot it, bad things would happen with the 90 thou shorter shoulder location of the factory 338 RUM.
I would get either a Lawton M7000 receiver or use a trued Rem 700. The Lawton will be a few ounces more in weight but its a much stronger receiver as well and is ready to build on out of the box.
Barrel wise, I would look at something like a 1-10 twist #4 Lilja. With a 338 bore through it this would not be an overly heavy barrel. You could drop to a #3 but I personally would prefer a #4.
The 338 cal is very efficent and will get most of its velocity potential in a 25" class barrel easily.
Stock wise, personally I would look at either an H-S sporter or a McMillan sporter stock. Manner also makes a very nice lightweight stock depending on how light you really want the rifle to be.
If you will only use up to a 225 gr bullet, the 1-12 twist will probably be all you would need but it never fails that somewhere down the road you will want or need a heavier bullet and the 1-10 will handle anything up to 300 gr so that is what I would recommend. It also shoot the light weight bullets very accurately as well so you will not give up anything in accuracy.
If your only looking to shoot out to 500 yards, there would be no problem at all getting a light weight rifle to easily hold moa out to that range and generally much less then that. Just depends on how light you want to go.
As far a brake, go with a Defensive Edge or Holland. Best big game brakes I have ever used and unless I use one of my own designs, I always use Defensive Edge brakes now.
Kirby Allen(50)