Winchester introduced .338 WM in 1958 and the .300 WM came later in 1963. Remington introduced the .338 RUM in 1999 and later followed by the .338 RUM in 2001. Yes, Remington screwed up. Shawn Carlock was smart to realize Remington’s shortcoming and came up with his .338 EDGE in 2001.Bergers load data is castrated. Nosler shows 2700s. If you load longer coal, I'm sure 2800 is on the table.
This is my issue wth the 338wm. Bigger+ less aerodynamic bullets with less case capacity than the 300wm. Same issue with the RUM and Nosler cartridges. I'm certain its for legal reasons because it makes no sense otherwise.
Good luck in your search.
I do not think the .338 WM was designed to propel heavier than 250g at long range beyond 5-600Y. As noted, I have similar rifle as @Hoss50. I experimented with the 225 and 250 NABs and settled for the 225. The Berger 250s/300s are pretty long for the rifle’s short COAL and insufficient powder capacity to propel them effectively at long ranges and desirable velocities.