My Sinclair gauge is the least used tool on my bench. If my rifles are shooting well, I don't gauge the cartridges. I used to do this regularly and very seldom found anything with a runout of more than .003. That's probably too much for benchrest guys, but when you're getting small groups from a hunting or varmint rifle, I'm satisfied with it. I use a Co-Ax press to load all rifle ammo; whether that has a bearing on anything or not, I don't know.
For those of you with experience in this area: if you're dealing with runout alone as a factor that affects accuracy, how much runout does it generally take to become a problem?
