Evidently, breaking the seal between the bullet and mouth of old, stored cartridges really does improve groups. I had some Lake City '69 M2 30-06 ammo to shoot up in my US M1 Rifle. This ammo was grouping 4" at 100 yds. I pulled 20 rounds and re-seated the bullets .020" off the lands of my rifle. The groups tightened up to 2" at 100 yards. I next tried using the seater to just break the seal, by seating just a tad deeper. I could hear an audible "snick" as I eased down on the bullet. I fired that batch and got 3" groups. I am concluding that although I knew that reseating closer to the lands would improve groups, I did not know that simply breaking the seal will also improve groups. Has anyone else observed this phenomena?