Well welcome to the board....
you are going to want to e-mail Chris Matthews. He's built probobly 150, 308's over the past 2 years. But ask him about the chamber and neck he cut for me... shoot factory Black Hill's into the 3's or better , it shoots my handloads into .2's consistiently.
He's done this for several people... and each 308 shoots the same... probobly better now that he's getting his barrels from Tim North( Broughton Barrels)
his e-mail is firstname.lastname@example.org