The fuss over .338 Lapua

[AusTac]

You see marksmanship skills transfer with the caliber of the rifle, if its a .50bmg = pro .338 = semi pro

[andreweden]

Template differences between 338 lapua and 300 WM are no different.
338 just has long range stability and accuracy - that's all.
Rest is BS.

So where is this actually written down?
How are the templates determined (my assumption is that the round has to be under a certain velocity and/or energy before it gets X metres downrange for the case that someone shoots over last stop butt?)

SSAA Ripley allows 300WM but not 338 Lapua. Does this mean it is the SSAA that has an issue with .338?

I don't have an issue with rules - I just want to know where they are and who is responsible for them.

[andreweden]

For arguments sake -

Hornady 338
Test Barrel (24") Velocity (fps) / Energy (ft-lbs)
MUZZLE 100 200 300 400 500
2745/4768 2630/4378 2519/4015 2410/3676 2304/3359 2200/3064

Hornady 300WM
Test Barrel (24") Velocity (fps) / Energy (ft-lbs)
MUZZLE 100 200 300 400 500
2850/3607 2702/3243 2560/2909 2421/2603 2287/2323 2157/2066

The 338 does have 50% more energy at 500 yards despite the velocities being similar.

So what are the limits when it comes to a particular range?