As they say, always read the fine print!
While a 300 yard zero might make sense in practice, I've never heard of factory ammo using it is standard! Not saying it's misleading, it's not, but it does certainly make their stuff look better haha.
This reminds me of LAZZERONI arms' ballistic tables. Don't get me wrong, those cartridges kick serious butt and led the charge towards non belted ultra capacity magnums in general, truly awesome.
BUT….their data was for Arizona atmospheric conditions. Again, that's not misleading, they are after all from Arizona! HOWEVER….
At 5000 feet elevation and 100 degrees Fahrenheit even something so pedestrian as my boring old 300 win mag can be made to look pretty dang flat! Compare it to ballistics from sea level, in cold weather, at high humidity and it definitely changes the trajectory and energy numbers, especially as distance increases.