For my BFR I use Starline 500 S&W Mag brass and cut it down via a DIY jig and hi-speed arrow cut off saw. Finish up with a Redding case trimmer. For dies I use RCBS 500 S&W Mag, and yes Lee will make a custom factor crimp die which I have and works as advertised. I set mine up for the Swift 325 AF at 1525FS using Accurate #9 and CCI-350?s.
D..

NRA Patriot Life Endowment
HHI #6544