Re: Hybrid 100 in the 340 wby or .338 ultra mag.
This new powder is not yet available here so I have not worked with it. It would be my opinion however, after reviewing Hodgdon's website, that it is a bit fast for either of these big cases. They do list load data for it in the smaller .338 WM but it doesn't deliver any more velocity than is attainable with other powders such as H4350 or H4831. While it is of appropriate burn rate for the .338 WM, you could probably beat it with a slower powder in the cases you mentioned. Good luck on your hunt.
"Fenced yards ain't hole cards and like as not never will be, reason for rhymers and old five and dimers like me."