Lapua Guy,
In a quality rifle with good ammo and shooter, there is no difference at all between the Lapua, the 338 RUM or Edge. I assure you that my numbers do not come from any CPU except my own. I realize your new here and I have not gotten the reputation I have by repeating numbers so instead of taking offense to your uneducated comments toward my experience I will give you a pass.
The Edge and the Lapua have identical case capacity, infact some lots of RUM brass will have more capacity then the Lapua.
If both are loaded to 65,000 psi which is their designed pressure ranges, they will be identical. If you hot load the Lapua just because the case can handle it you will get more velocity, big suprise. That does not mean its the right thing to do.
I would say your troubles with the Edge have to do with something in the rifle or the bullet your using. THe TTSX bullet is well known to shoot well but also it can be a very finicky bullet depending on seating depth, again, well know. I have built well over 100 Edge rifles. I use one load, 93.0 gr Retumbo under the 300 gr SMK and lit with a Fed-215 primer and seated to 3.780". I have never had one that EASILY met my 1/2 moa accuracy standard when I accuracy test my rifles before I ship them to my customers.
I have never had a problem with the Lapua either, nearly identical load.
I have never had a problem with the standard 338 RUM either, all have easily broke 1/2 moa out of freshly machined barrels.
Try a bullet that is far less sensitive to bullet seating depth and you will likely find that there are no consistancy issues with the Edge, RUM, Lapua or any other 338 magnum chambering.
Make sure the receiver is square, cut the thread fit tight and on axis, cut the chamber to min spec and on axis, make sure the throat is designed well and cut on axis and cut the crown to match specs, bed the receiver to the stock properly and you will have a sub 1/2 moa rifle no matter what the chambering is as long as the ammo is straight and shooter is up to the challange.
Simple as that. Rifle manufacturing is not rocket science. Neither is building a precision rifle, just more attention to exact detail is all, nothing more nothing less, case design has very little to anything to do with rifle accuracy in chamberings of this size class.