Closing the loop on this: the issue turned out to be that the lower holder/collar in the FA seating die was gripping the bullet very tightly during seating, causing several simultaneous problems including holding the bullet canted, which caused the bullet to "grip" the seating stem and pull it...
100% agree with this concept.
My only nitpick is to mention that someone else's measurements are irrelevant as long as your only concern is consistency (which is almost always the case in reloading). It's not important what the *true* CBTO or COAL measurements are, unless for some reason...
They do not. The cone in the die is (or certainly should be, anyway) quite a bit steeper than the cone of the bullet near the tip, so the die grips the bullet along a ring a little below the tip itself.
I don't have any evidence for this, but my gut says that MOST of the variance in seating depth (and the resulting COAL) is due to the variance in concentricity when loading. If concentricity is off, then length will be too, regardless of whether you're measuring to the ogive or the tip.
This...
Love all the love for the 7mm-08! 😍
'Tis also my beloved, but I'm not sure it's "bigger" than the 25-06 😅.
6.8 Western or 300 WSM? Availability is pretty good around eastern WA so 🤷🏼♂️
☝️
And you often don't need 30 shots to tell if it doesn't like it. If you're going for a 1/2 min load, and your first 5 shots print 1.5 min, move on to a new bullet/powder combo. But if you get 1/2 min (or 3/4), keep shooting and see if you're still satisfied.
Normally the ladder method is supposed to help determine accuracy by identifying "nodes" where the velocity flattens across a range of charges before continuing upwards. The idea goes that you've found a spot where the muzzle velocity (and thus the "dwell time", which purportedly controls where...
The bullet-powder combination is king. There is ample evidence that presumed differences in accuracy seen in small-sample methods (e.g. latter tests, OCW, etc) disappear if you keep shooting. In other words, jump/COAL and charge weight have negligible effects on accuracy.
Your main problem is that ladder tests are hot garbage in the first place; don't waste your time and $$.
Load up 3-5 rounds in a middle-of-the-road charge. If you don't hate the accuracy, then start creeping up in charge weight to get to the velocity you want, understanding that other things...