This is what I did to cut down a 460S&W factory crimp die to fit the 454 Casull.
Screw your 460 die partway into a press. take a punch and a small hammer to tap the collet insert out of the die body. Go easy and don't break anything.
Once they are apart, take a sharpie and mark the die body at 2.000", mark the collet at 1.285".
Cut them off with a hacksaw, dremel, lathe, anything that can make a nice cleah cut.
Be sure to cut the collet a little long, so you can fine tune it to get the crimp where you want it. Mine is finished up at 1.285"
Be sure to debur your cuts.
I took a set of number punches and marked the collet 454.
Clean everything up and slide the collet back into the body and give it a try.
Let me know if anything is not clear.
Here's a link to the 450 Bushmaster forum where they are talking about modifying Lee FCDs to do a Legendre side crimp to help hold cast bullets firmly in the case.
Lots of pics and step by step instructions.
http://www.450bushmaster.com/viewtop...5&t=685&p=4564