hbb: Pretty sure it would, from what I remember about the 400H&H.Point is buying brass from H&H could get a bit dicey and expensive; whereas 375H&H for forming is all over the place.
KDK: Can't answer your comment, except to say maybe 416 still leaves a shoulder...is that good or bad? I don't really know...this is a case that needs that useless belt in any event.
I guess 404 bullets are made by enough outfits today.
What I found interesting is the velocity of 2225 with the 400 gr bullet and (what?)only 68-69 gr of powder? That will translate into a very manageable package from a recoil perspective. I bet this thing will be sweet to shoot even from a handy 22" barrel.