A lot of the time, it is not the dies that are having the problem, but the press is not allowing shell holder, case, & die to line up.

Measure the runout on a loaded round. 0.002 is ok. 0.001 is very good, if achieved consistently. Less than 0.001 runout is awesome.

Now, couple that with IF you have a straight and true cut chamber, bolt/bolthead that are allowing everything to center, and good contact with the back of the lugs.....THEN you are in business.

As far as accuracy, some barrels, it seems, pour some sand in, find a primer to light it, and push the blemish 55 gr full metal jacket....and the barrel shoots bugholes with range pick up brass.

The next barrel, that you custom ordered, coupled with the lathe turned bullets, special brass imported to Sweden, drawn in Switzerland by their sniper team, with VV powder....and you are shooting 3" groups!

Call it luck? :)