I don't believe in seating bullets to "just touching the rifling", particularely with production bullets.
First of all, production bullets (and customs to a lesser extent)can only be produced within certain tolerances. Base to ojive distance varies, curvature of ojive varies, bullet length varies and on and on.
Additionally, it is difficult to get an EXACT measurement of your chamber/throat with the current maesuring tools. If you are within 1-2 thousandths than thats pretty good, but you also have to remember that the throat is always receeding slightly too. It doesn't take much for a throat to erode .001".
Given the inevitable variences of a few thousandths, if you try to "just touch the rifling" than one round may do just that while another is .001" into the rifling and another is .001" off the rifling. That is three very different conditions, and all within .002" of variation from bullet base to bearing surface of the bullet.
I much rather work .005"-.010" into or off-of the rifling. This way a variation of a few thousandths will not cause a significant change in engagement.
Sako7STW,
Provided that the wind is favorable, group size changes are normally more evident as range increases.
Just my thoughts - VH
[ 02-27-2004: Message edited by: Varmint Hunter ]