Shortening the die is the best way that I've found (loaded 444 Marlin). You can also use a Lee FCD with the bullet upside down in the top of the die, but it's not all that easy and is pretty annoying. You can also check with Hornady, they may have a custom crimp die for the round (or can make one if not, Lee also makes custom dies if you ask from what I've heard). Otherwise, careful use of a grinder with a normal FCD may be the way to go.
Just a side note, as I have a single-shot, I don't need to trim to the shorter length (fits fine in my handi rifle using normal 444 length instead of LE 444 length), so I only have to deal with this on reloaded factory cases for FTX loads... Depending on your gun, you may want to try loading a couple to normal 45/70 length and see if it works for your gun. Lever guns probably won't cycle. The pressure would decrease from their posted powder weights, so you may be able to squeeze a little more out of them with the longer shells as well, but you'd have to work up carefully.
Good luck!