I wouldn't think so.
Really, a magnum action is required only for the 505 Gibbs although it is nice to use a magnum length action for the 416 rigby too.
I have seen a lot of 404's on magnum actions - and I would like one of course - but to my mind, the magnum action is for accomodation of cartridge length, not power/pressure.
After all, even my 500 Schuler is on a standard action.
My Evans doesn't even have the right side of the stripper clip bridge taken off such as Jeffery 404's do - just the little protrusions that point inward which hold the stripper clip in place were taken off. Cases load, cycle and extract with no problems at all - OAL of the 404 fit fine in the standard action.