PDA

View Full Version : Bearing surfaces and seating depths



thekubiaks
07-18-2010, 04:45 PM
I sorted a large group of bullets using a bearing surface comparator. I cam up with three main groups. So, if I decide to seat the bullets .010" into the lands, do I need to adjust my bullet seating die for each bearing surface group? If I don't I will be +/- .010" into the lands using the other groups with no adjustment to the seating die. Do I have that right?? Thanks.

eww1350
07-19-2010, 12:31 PM
Since the bullet seater contacts the bullet along the ogive, the seating depth should remain constant in your loaded round. I suggest measuring a few loaded rounds from ogive to base of the case..I think you will see very little variation...

thekubiaks
07-19-2010, 12:58 PM
Thanks for the reply, I just got back from the range this morning. I shot several 5 shot groups with bullets having the same bearing surface reading. (7mmSTW, 76.5gr Retumbo, GM215M, .012" neck, .001" tension, JLK 180gr VLD, 3019fps, Krieger .310neck, 1-8.5 30"HB) Amazingly, my ES dropped to < 5 fps for both groups. Accuracy improved too, .416" @ 200 yards. For me, this is another step forward, its off to 1000 yards to see if the group size will stay down or if it was just a fluke. Regards.