IDMilton,
You will get lots of answers here about the "best" dies to use. The truth is that lots of dies will get you where you want to go. As an example, my 6mm PPC benchrest rifle will average in the high "teens" with the right load (that's 5 shots at 100 yards) despite some use on the barrel. I don't use it for benchrest matches, but for testing various aspects of accuracy--and occasional prairie dog shooting.
Serious benchrest competitors don't even use a conventional press, instead using very precise "hand" dies and an arbor press. But this is a slow way to load. For putting together prairie dog rounds I use Redding Competition dies in a Redding T-7 turret press, to load the ammo reasonably quickly in quantity. The MOST bullet run-out I've measured in my loaded ammo, even with this set-up considered imprecise by most benchresters, is .0005". That's one-half of one thousandth of an inch, with essentially mass-produced handloads. But I am doing more than just using good dies, like neck-turning.
You will have to incorporate other stuff than a mere change in dies for real improvements in your loads, and as some other people have suggested a concentricity gauge is the very first purchase you need to make.
