Originally Posted by ss7mm
Is it the same seating die as before?
Are you using the same bullet as before or a different bullet?
Reason for the questions is, have you checked to make sure that the tip of the bullet is not being hit by, or bottoming out in the seating stem? You'd have to take the seating stem out to check but if the die/bullet combination is the same as before then this probably wouldn't be the problem.
Do you have measured dimensions of the case necks after prep in the before instances? Do you know the neck thickness before and now? Do you have before and now dimensions of the case neck prior to seating and after seating? Just curious as to whether anything in the neck area has changed. How many reloads on the brass?
And I'll agree with you on the runout. I try and keep mine as low as possible.;)
I discovered the problem as part of a test to see if neck turning would improve on already low ES. I am using Lapua cases, the neck turned cases had a .014" thickness and the unturned cases ran .015-.016".
I am using the same bullet as before, Berger 168gr VLDs (.308) I ran out of the old lot, so this is a new lot of the same bullet. Bullets are sorted by bearing surface length.
The bullets do not bottom out in the Redding competition seater die, I am not sure about the standard die but I got similar runout readings from both so I am leaning towards ruling out the die.
I think I am going to borrow a friends press and load a few with my dies, if I get low runout on his then I am stuck blaming the press even though I can not figure out how that would have happen.
FWIW, on 20 neck turned cases, 18 had .006" runout and 2 had .007", very consistant and maddening!