Color me stumped. I am reloading .308 Lapua brass with both Barnes and Hammer bullets. Brass was prepped with a Redding body die, and necks were sized using a Lee neck sizing die. I checked my brass after those steps and runout is basically nonexistent. I am then using a Forster Micro-seating die, and I am getting runout that fluctuates between essentially zero, to some that approach .007. I'm seating them carefully. I've tried seating part-way, turning the cartridge, and then seating the remainder of the way. The runout seems pretty random to me, as there are loads that are perfect. Any thoughts?
Strange, I'm using run of the mill cheap RCBS FL dies, that you can buy at Wally world. Those dies produce .003" and less TIR. That is with Sig Sauer 308win brass (since you are asking about 308 win). What concentricity gauge are you using? Sounds like your seater may not be adjusted properly, as that is when the poor TIR is seen in your set up. According to the OP.
A while back, my girlfriend was watching me load some ammo, and she asked a very valid question. She was wondering why my ammo shoots so much better than factor ammo. I pulled my concentricity gauge out, showed her how to use it. Had her spin some of her factory loaded .223 ammo for her AR, and the needle was jumping all over the place. I then handed her a box of my 308 win loads with 175 SMK's. She put one of those in the concentricity gauge, spun it, and said the gauge was broken. She said the "needle" was not moving. I said, dang it, try another one. She said, "same thing". I said, try a few more, you'll find one where the dial goes up a little bit. I then had to explain to her, what she was seeing. The ones where the "needle" was not moving, or just barely going up were the ones that were perfectly straight and very concentric. I told her that all of my ammo is like that, because I have my dies adjusted to minimize runout.
Moral of the story: You don't need fancy or expensive dies to produce absolutely straight ammo. You also don't need Lapua brass either. There are other brands of brass out there, that has worked just fine for years.
A lot of concentricity issues most guys see is because they don't have their dies set up properly.