I had an experienced hand loader visit my place the other day looking at a gun I am selling. Got to talking about hand loading and why I can't get the groups I want on a 300 WIN mag. I shot some 300 yard groups recently and they were all a little over MOA. He noticed the following: Neck sizing ball was not centered in the die, not even close. My bad. The neck opening on the brass is not square to the case. He says this will cause more tension on one side of the bullet than the opposite side because there is more brass in contact with the bullet. He said to trim square even though the over all case length will be shorter than published specs. He took a few loaded rounds home to measure and said concentricity was not good, probably because of the uncentered die. He recommended a Lee Collet Die, RCBS case master and a neck turning tool. I trust about 99% of what this guy says but I wanted to confirm here before I buy more assessories. Thanks!