Yes, it seems odd to me as well. When Rem. introduced the 338 version, they said they made it shorter because alot of the 250-300 grain bullets are extra long, so to seat them properly. I don't know about that. That is why the 338 Edge is out now, which uses the 300RUM case & is a screamer. Plenty of info on longrangehunting about it.
The one that should have been shorter is the 7mm, too much powder for caliber. It won't outrun the STW by an appreciable amount unless you load the heavies with a long, fast twist tube.