I've had pretty good luck loading the 250 grain FTX and the Sierra 250 grain JHP in cut down .284 brass using no expander, and no side crimp, just the Hornady taper crimp die to .478 You have to be careful to help the Hornady seating die align the bullet to the case before you seat it or the mouth of the case will scrape some copper. I never use the Hornady expander die anymore as it's too large in diameter, and there's no easy way to polish it down. I use a Lyman "M" die to expand cases for the .453 cast boolits just enough to seat them without shaving lead, and then side crimp them. I haven't had any good results using the Hornady brass without a side crimp.
BD