RE: 338 Ultra Mag ..who has one?
My brother-in-law has one, a Remington African Plains Rifle. The recoil is noticible but not terrible. I loaded him some 200 gr Hornadys. Very accurate, less than 2" at 200 yds.
He shot a cow elk and broke her back, so not much of a test there.
He shot a little deer with it in November. Caught him head on. The bullet went right down the spinal column, penetrating one vertebra after another, about 9-10" of bone. Bullet was lodged in the backstrap, have not weighed it yet to see home much weight it lost.
Hope this helps.
KC