Big one is keeping your finished ammo concentric. If the bullet engraves in the rifling wobbly, guess what - wobbly when it leaves the pipe. Not so good.
The least expensive die set I use that gives superb results is a Lee collet neck die for neck sizing. A redding body die to just push the shoulder back when it gets sticky to chamber.
The big mystery - the seating die. I have used RCBS and Lee with excellent results. If the part that contacts the bullet to push into the case is well shaped to the shape and bullet tip length, you can seat with runout under 2thou. Unfortunately, I have found that I get the occasional one that is up to 5 thou out.
Does that matter? Depends on the bullet, the chamber/throat, the barrel and how far you plan on shooting.
I have shot ammo with as much as 8thou runout into 3/4" at 200yds. I did this just to burn off the wobbly bullets and voila, great group. However, lower runout is definitely better.
I try and keep all my match ammo at 3 thou and under. Seems to allow me to shoot in the 1/4 to 1/3 min range at 300m which is plenty for F class.
Weighing your powder charges to keep to very small ranges is a great way to reduce groups. I also use match primers or whatever shoots the best testing at 200yds and further. Watch for vertical stringing.
Adjust your powder charges in very small increments. 1 tenth for 223 sized cases, 2 tenths for 308 sized cases. With an accurate rifle and good shooting, you can see the differences. I don't play with seating depth as I usually feed from the mag in my hunting rifles and just set off the lands for my match guns.
I am about to try another Forster seating die to see if I can get more consistency at 2 to 3 thou runout. If not, I will also get a Wilson.
Most factory/semi custom rifles will not see much change in a thou of runout but it sure helps builds confidence.
Jerry
