The few 404J 400gr cast bullets I have bothered to dig out from a sand backstop at the range have shown some expansion. These are cast from Lyman #2 alloy and shot at 1800fps MV, down range distance 50m. Unless hitting big bone I wouldn't expect much expansion in an animal and the few deer and feral goats I have shot with the 404 have been pass throughs with no visible sign at exit of any great expansion. I've shoulder or head shot the animals with the 404J so pretty much died from organ trauma without expansion. Then again I've done the same thing on same game at close range with a 455 Webley revolver and cast 250gr bullets at a little over 600fps. The 455 bullets were round nose with a small flat meplat.

I think a hollow point would help with expansion in the 1800fps MV range.