I use an RCBS setup and RCBS dies except for .44 Mag (Lee dies that a buddy bought, it's his gun). I know nothing about the .308x.444 cartridge, but it sounds like a JDJ type cartridge. He based all of his on the .444 Marlin. Get your stuff and setup a sturdy worktable and a quiet place to work to start with. Try a couple of different powders that are in the appropriate range. I think Hodgon offers 'try packs' that have like 4oz of each of 4 powders. the .308 is a popular enough round that you should have no problem finding an appropriate powder. Aside from trying different powders, the biggest thing that can influence accuracy is OAL. Most people say start .030 off that lands and work from there.