Quiet Tex
Here's my email question to John Whidden...
I already knew that John. Guess a better question is, the tool you make or any other comparator that measures from the ogive, as the throat erodes, changes where it contacts the ogive. As the throat erodes, it contacts the bullet farther down towards the base of the bullet? Would you agree?
His answer... Yes, I expect so. It seems reasonable to think that the diameter of the throat erodes.
I would 100% agree. The usefulness of bullet comparators is predicated on the assumption that the comparator measures a different point along the ogive radius than the actual lands/ogive interface point. At any given point in time that's a static difference, but over the life of the barrel certainly changes.
Bullet comparators are IMO much less susceptible to tolerance errors in the comparator hole because the measurement you're either -
1) taking from the chamber using the Hornady/Stoney Point tool, one of the split case/bolt jam methods, from a chamber cast, etc; or
2) taking from loaded rounds set to a certain BTO/COAL
- is not an actual measurement of the interface point.
The measurement is always relative and will always be moving. The target spec for seating depth is commonly 0.001" increments because ogive and bullet length tolerances don't let you get any better without a ton of sorting work. And sorting bullets like that is work that doesn't show up on the targets unless a whole lot of other specifications are perfected, as verified by a lot of talented shooters whos' results and presented data I trust. Not saying it doesn't matter, but the results are hidden inside noise from a lot of other processes.
Now headspace comparators (the original topic up above) measure a dimension that won't significantly change over the life of a barrel, so chasing both precision and accuracy here could ultimately be useful since setting of headspace/ cartridge resizing dimensions in a chamber doesn't need to change over time. You can increase brass life and increase accuracy with more precise control over case sizing, especially when paired with a well cut chamber. But unless you're trying very hard to resize in very small amounts, there's no need for an expensive tool with a higher accuracy level.
But at least I admit the stuff I'm nuts about is nutty and isn't always practical, right?
