If you ever shoot old ammo it is wise to bump the seating of each bullet as they tend to weld themselves to the neck. If you bump ,lets say .002 it should be enough to give you the neck tension you started with. By having the welded problem pressures can vary wildly.That may answer why you were getting high ES and SD. A lot of benchresters who preload for a match seat them long so when they get there they can finish seating and have the same smooth release of the bullet during ignition to get optimum performance.
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