You need to adjust the die down until your bolt just closes on the sized case without force or slop. Two ways to do it; use the rifle itself as a gage or use a gage made to measure the case.
Adusting our 14 threads per inch dies can be difficult because a seemingly tiny change makes a LARGE difference. Most rifle head space tolerances run about 10 thousanths, max to min. A 1/16 turn makes a change of about 9 thousants! This HAS to be done slowly and carefully.
Using the rifle as a gage, simply back the size die out from shell holder contact about a quarter turn and size a case. Try to chamber it. It probably won't chamber easily (if it does back the die out another quarter turn and try again with another case). Assuming it is too tight, turn the die down another 1/16 turn and try chambering again. Keep this up until the case chambers easily and then back the die out 1/32 th of a turn and try it with another case. Continue back and forth, with fresh cases, until you get the fit you want. Lock the die ring to allow you to return to this precise setting easily.
Case gages such as the RCBS Precision Case Mic, Sinclair's case measureing tool, or the Hornady/Stoney Point case tools all work well. You can simply measure the case length from head to shoulder. Then adjust the size die to either match the fired case length or a thousanth or two less, as you wish. (The lengths won't ever be completly consistant, the brass in each case will spring back a little differently, so settle for a good average.)
After the sized body and shoulder are where you want them, the Lee Collet Die will get you some very straight necks!
Last edited by boomtube; 05-14-2008 at 08:42 AM.