06shooter, you want to be consistent with measuring ogive to rim?
I think you're overly concerned about a cartridge dimension that in reality, is not super critical for even the most accurate shooting known to man. While it's easily measured and the numbers may seem big, in reality they're way too small to make any measureable difference in accuracy.
If you shoot a single few-shot group with one dimension set up, then change it .005" and shoot another few-shot group, the odds of that .005" change making a difference are very small. You'll see the same difference in group sizes across 10 other few-shot groups with the same setting on your seater die.
The only way to get the same bullet jump distance to the origin of the rifling for every shot is to size cases with minimal neck tension on seated bullets, then seat bullets out far enough that they're set back into the case neck as they are pressed into the origin of the rifling. Jump distance is always "zero" when that happens.
Anytime there's a space between the bullet and where it first touches the rifling, it won't be exactly the same for every shot fired. One other variable with bottleneck cases headspacing on their shoulder is shoulder setback. That happens when the firing pin drives the case shoulder hard into the chamber shoulder. What happens is exactly the same when sizing a fired case in a full length sizing die. The case shoulder gets set back and that moves the bullet a few thousandths inch closer to the rifling before the round fires. The slight shoulder angle and smaller shoulder area of the .30-06 case compared to others lets it often set back .005" from firing pin impact.
You can easily measure that, Disable a primer with a drop of oil, seating it in an empty case, then measure the case headspace with a suitable gauge. Then chamber that primed case in your rifle and shoot it; the primer will not fire but the force of the firing pin slams the case hard into the chamber shoulder. Extract that case then measure its headspace. Note the difference from before it was fired. Example; 2.049" before then 2.045" after which is a .004" difference. That difference is how far the bullet gets moved forward in the chamber before its fired.
I've never been concerned about that .004" spread in such stuff with my .308 Win. match rifles. Therefore, I don't think it matters with someone's .30-06.
I think you're overly concerned about a cartridge dimension that in reality, is not super critical for even the most accurate shooting known to man. While it's easily measured and the numbers may seem big, in reality they're way too small to make any measureable difference in accuracy.
If you shoot a single few-shot group with one dimension set up, then change it .005" and shoot another few-shot group, the odds of that .005" change making a difference are very small. You'll see the same difference in group sizes across 10 other few-shot groups with the same setting on your seater die.
The only way to get the same bullet jump distance to the origin of the rifling for every shot is to size cases with minimal neck tension on seated bullets, then seat bullets out far enough that they're set back into the case neck as they are pressed into the origin of the rifling. Jump distance is always "zero" when that happens.
Anytime there's a space between the bullet and where it first touches the rifling, it won't be exactly the same for every shot fired. One other variable with bottleneck cases headspacing on their shoulder is shoulder setback. That happens when the firing pin drives the case shoulder hard into the chamber shoulder. What happens is exactly the same when sizing a fired case in a full length sizing die. The case shoulder gets set back and that moves the bullet a few thousandths inch closer to the rifling before the round fires. The slight shoulder angle and smaller shoulder area of the .30-06 case compared to others lets it often set back .005" from firing pin impact.
You can easily measure that, Disable a primer with a drop of oil, seating it in an empty case, then measure the case headspace with a suitable gauge. Then chamber that primed case in your rifle and shoot it; the primer will not fire but the force of the firing pin slams the case hard into the chamber shoulder. Extract that case then measure its headspace. Note the difference from before it was fired. Example; 2.049" before then 2.045" after which is a .004" difference. That difference is how far the bullet gets moved forward in the chamber before its fired.
I've never been concerned about that .004" spread in such stuff with my .308 Win. match rifles. Therefore, I don't think it matters with someone's .30-06.