I like to use the one that corresponds to the reamer print on any case. That said, in my experience using the .350 or .375 Hornady comparator can give you what you're looking for. According to prints, the 6BR has a .375 datum too. I wish the comparator that came with my Whidden Dasher dies was engraved so I'd know which number they use.That’s what I’ve read but doesn’t seem to be a consensus on what people are using.Anyone want to share numbers ther getting?I realize all inserts are different .
My Whidden FL bushing die bottomed out too. I called and they said send it in with a couple pieces of brass. Turned out it missed a step in manufacturing and they replaced. Not complaining; in fact, I was very impressed with their honesty and fast CS.Been using .400. Will try either the .375 or .350 a try to see if it makes any difference.
Ordered a Forster FL Dasher die and had to send it back because it was bottoming out on the press (COAX) without setting back the shoulder. Was using a Redding Type S FL die with a .265 bushing without the expander which gave me 30 psi of seating pressure. Had Forster ream the neck to .265 while they had it to trim. Set it up this evening and checked runout on three cases. All three cases had runout at the neck of .0005 or less using a Accuracy One Concentricity Tool and Starrett dial test indicator. Think I am going to like the die.