338 Lapua as mentioned is a more powerful cartridge then the 338 Win Mag. Think 250 gr bullet at 2960 fps (26" bbl) vs. 250 gr bullet at 2650 fps (which is typical of actual 338 Win Mag velocities from a 24" bbl). Be aware that factory Lapua ammo only pushes that 250 gr bullet at 2750 fps though. I too shoot a Sako TRG-S, good rifles, except I don't care for the recoil lug set up. They are heavy, but in this cartridge that's a good thing. As mentioned, the RUM will give you the same performance level at much less expense, but it doesn't have the "rep" of the Lapua cartridge. I don't know if Sako is still making the TRG-S anymore, I haven't seen one in a shop in a long time. Ballistically speaking, the Lapua is pretty much the same as the 340 Wby (yes, I have one of those too), it should be faster due to case capacity, but I haven't found that to be the case in the real world. FWIW - dan