LC brass is some of the heaviest 308 brass available, and Win one of, if not the lightest brass available. LC has more than "a touch less" capacity. Combined with using a magnum primer would echo Uncle Nick's advise. Whenever there is a flat spot in velocity curve, am getting very wary, especially if your velocity's are up there beyond load manuals. Instead on relying on pressure signs, would be putting the money on recorded velocity comparisons for load limits, and group size over es readings.
Depending on your purpose for the rifle, may influence how you test for accuracy. If it is a hunting rifle and you expect to use both hands on it, might consider testing it that way and 3 shot groups are plenty.
Depending on your purpose for the rifle, may influence how you test for accuracy. If it is a hunting rifle and you expect to use both hands on it, might consider testing it that way and 3 shot groups are plenty.