I have an old(er) 1894 Marlin in .44 Mag that I use for Cowboy Action shooting. It will digest anything with a j-word bullet but is very particular about cast boolets. The only cast that it will feed with 100% reliability is the Lee 240 gr. RNL. I've had this rifle apart half a dozen times, cleaning, polishing and adjusting springs, but it's still finicky about cast boolets. Interestingly, it seems to like that 240 gr. Lee in a .44 Spl. case slightly better than the same boolet in a .44 Mag case!
Best regards
Doc