.300 WM or .338 WM?
If you have both, take the one you shoot best. And the other as a backup.
If buying and you already have a .308, .30-06 or 7mm RM that shoots well, I'd go .338 WM.
Currently working up loads for the new 155g .284" Federal Terminal Ascent for my 7mm RM and .280 Rem with the intent to take them this fall. If the loads don't work out I may take them again anyway. Have not taken elk with the .280 but have taken more with a 7mm RM than all my other rifles combined.
Currently shooting Barnes 175g LRX in my .300 WM. Have not taken an elk with that load but did drop a nice mulie buck with it. The buck was on the ground before I recovered from the recoil. Nosler 225g AB are my choice for elk in my .338 WM, but unnecessary - I use 225g Hornady SSTs for practice and think they would work just fine.
The .338 WM provides noticeably more recoil than my .300 WM, although both rifles are essentially the same - Ruger actions and barrels, Ruger boat-paddle (skeleton) stocks. Calculated recoil for the .300 is around 29 ft-lbs while the .338 about 36. By comparison, my 7mm RM is at about 24 ft-lbs with either my 140g or 160g loads, My .280 Rem is around 18 ft-lbs with a 140g Nosler AB The .280 load delivers more velocity and energy at 500 yards than a typical 150g .30-30 delivers at 100. If I can get the Terminal Ascent up to 2850fps at the muzzle, which should be easy based on my tests so far, the .280 becomes a viable elk rifle well past the 600-yard limit of my practice. Daughter #1 will be carrying a .270 Win with a 150g Nosler ABLR in her .270 Win. With a calculated 18 ft-lbs recoil, half that of my .338 WM, that load is also good well past 600 yards. (Both the .280 Rem and .270 Win loads deliver over 2100fps and 1500fpe past 700 yards at 7000 feet altitude.)
The point is, you don't need to put up with a lot of recoil to have an effective elk rifle/cartridge combo at typical ranges. If long range is your game, the .300 WM would be my choice. A high B.C> bullet, like the 200g Terminal Ascent, launched at 2950fps will deliver 2000fps and 2000fpe past 875 yards at 7000 feet altitude.
Get or use a rifle you like. Headstamps and bullets matter, but so does enjoying the hunt.
