QUOTE: I have a M1900. Very smooth. Have considered the .416 Taylor, but I got the feeling .425 Express offer better fps and frontal-mass. Tuzi R. :UN-QUOTE

Which ever one you deside on of those two the case to start with is the 338 Win Mag case! It is the same case as the 300 win mag, but has already had it's neck expanded to .338, so the jump to .416, or .425 isn't so big a stretch!