I've been loading for a number of years for various calibers but have never looked at seating depth as a first stage to load development. It always been 1.bullet 2.powder 3.primers(std vs. mag) 4.seating depth and I have plenty of rifles that shoot very good (.5moa-.75moa) using that order of importance with very little effort on my part.
I built this 6.5x55 with the intent of it being a .25moa-.5moa rifle and up to this point it has only been a high .5moa reliably. Unfortunately as my initial test results with Bergers recommendations suggest I may have been missing the boat when it comes to my reloading methodoligy.