Hands down my favorite hunting cartridge for Alaska. Took a moose two years ago at 437 yards. On moose, I typically hit them more than once, and try to miss the shoulders if I can to save on meat. This guy got a nice triangle pattern of three 250gr accubonds into a pretty little baseball size pattern--not bod for a lighter barreled hunting rig shot off my walking stick.
I've played with that rifle and a couple others out to 700 yards with great success. Love the round for hunting, but admit I haven't played with it much for real extended ranges. Hope to later this summer as I stretch the legs on a new rig Jarod at APA built for me last fall. It was one of my factory Winchester M70's in 338, now a little more tricked out and wearing a #4 contour barrel--which I wish I had either fluted or gone with a #3, came out slightly heavier than I wanted.
I will also say I have yet to find a 338WM that shoots the 225gr bullets well. They have all loved the 250's, shooting much, much better. I'm not an expert and cannot say why, have just had quite a few of them, and presently have 4--none have shot within satisfaction in a number of different 225's.
Almost forgot, my rigs in 338wm are dedicated hunting rifles, so I like a slightly shorter barrel for up hear as it's all spot and stalk. 22-23" is my favorite for barrel length. Good mix of velocity and packability. For twist. The new APA build has a Bartlien 1/9.5 twist. Pretty sure my Remington Alaska Wilderness rifles is 1/10. The two other Winchesters--have to say I haven't a clue--but shoot 250's beautifully.