With good presses and dies I haven't found much need to "square up" seating dies with various lock-ring-techniques.The catch, of course, is finding which presses and dies are "good."
Yes, RCBS made some poor dies in years past, but I haven't had any difficulty getting their recent seating dies to seat bullets straight--unless, of couse, the seater plug fits the bullet's ogive well..
In my experience seating bullets straight depends far more on uniform brass (especially neck-thickness), resizing that results in the neck aligned with the case body, and a seating die that keeps the bullet aligned as it's seated, with with plug shape, a bullet-alignment cylinder, or both.
