The 338-404 imp or 338 Edge has a design flaw and will not live up to it's potential, regardless of increased case capacity. Which is why Rem shortened it in an attempt to hit the powder capacity sweet spot............they didn't. Those of us who have played with this case for over 30 years as I have, have known this for 30 years. The 35-404 Imp is amazing but the 33-404 Imp will not improve on the Wby even though it does have significantly more case capacity. This is a syndrome the 8mm Rem Mag suffers from too, and it never lived up to it's potential either or rather couldn't live up to it's supposed potential. Some cartridges have this bore/case capacity flaw and they will not exceed similar cartridges with less capacity. I can and did everything an 8mm RM would do with a 300 Win mag with the same bullet weights, 200 and 220 grns, when both loaded to the same pressure the several 300 WM I have had have outdone the big 8 every time. I cannot tell you why, but I can tell you that Ackley knew this as well, and so did Roy Weatherby I suspect, hence the radiused shoulders on his cases.
Anyway I may have to but this on my project list and build a 338 WM load 'er up, then chamber out to a 340 Wby and load 'er up, and then chamber out to the 338 RUM, and then the Edge and see how they compare in the same exact barrel.............I have done this before but not in the 33 bore.........The only true honest comparison of same caliber different capacity case/velocity potential.