I've had 2 .318 rifles, a Greener & a Jeffery, both made on Mauser 98 rifles. Both rifles were completely made in Germany, as evidenced by their proof marks. I've also had 2 .35-06's [aka Whelen]. One was a German "cigarette" rifle in 9x57 that was re-chambered to .35-06; the other is a Holland & Holland in .318 N.E. that was re-bored to .35 because of a ruined bore. I also had a .338-06 that was a lot let hassle to shoot as I did not have to mess around with re-sizing bullets.
I used 250 grain .338" Winchester Silvertips that were squoze down in a Z-Hat die in the .318's.
In the .35's I used old Hornady 275 grain RNSP bullets, as well as 275 grain Winchester Silvertips and 275 & 310 Woodleighs.
In the .338-06, I used 250 grain Winchester Silvertips & Hornady RNSP bullets.
Almost all of them are now gone & in their place I use either one of my Husqvarnas in 9.3x57 or my .366 Mauser Husqvarna [9.3x62].
As has been mentioned, in order to achieve the same sectional density as the 250 grain bullet in the .318, you have to use a 310 grain bullet.
When you do that however, I was only able to attain ~2,300 fps in the 24" barrel.
Does that matter? Probably not, as long as you are using quality bullets.