there is website dedicated to 6mmbr and they got tons of information about benchrest shooting and cartridges, here's a link to 6mmBr page where you can find tons of information to start on your project.

http://www.6mmbr.com/6mmbr.html

I use combination of Forster Bench Rest 2-Die Neck Sizer Set, paid 70 bucks for it and Redding Type S Bushing Full Length Sizer Die 53 bucks, plus bushings about 13 - 24 bucks a piece. 6mmBR using small rifle primers and you want either CCI 450 or CCI BR4, I buy BR4 only.