My Marlin 1894 in 44 mag shoots 240 grain bullets best. Over 18.7 grains of 2400 (Alliants listed max) I get 1500-1600 fps depending on the bullet shape.
It's favorite 240g bullet seems to be a Montana Gold JHP.
http://www.grovestreet.com/jsp/onepic.jsp?id=1066975