That's exactly what I meant - you CAN'T transfer that rim to ogive measurement, taken with your comparator, from one type of bullet to another. The comparator you describe is the Sinclair tool, same one I use. Trust me, the spot on the comparator that makes contact with the ogive is NOT configured and dimesioned exactly the same as the throat of your rifle. So, the measurement is not trasnferrable to bullets with a different nose geometry. It can't be.
Use the method you described for actually definitively locating the seating depth at which a particular bullet is making contact with the lands of your rifle. Take a rim to ogive measurement with your comparator. Now, repeat the process of locating the lands by smoking a bullet (or however you prefer to find them), with a bullet of a different type (just for clarity, make it really different - secant vs. tangent ogive, of different calibers 7 vs. 9 for instance). Now, take the rim to ogive measurement of that one with your comparator. It will measure differently than the first one did. Like I keep saying, unless your comparator matches your throat perfectly (it doesn't), the two bullets have to measure differently when both seated to the same relationship with the lands.
This is one of the most common misconceptions in handloading. I've even seen it presented wrong in fairly sophisticated "precision oriented" handloading publications.
By the way, just for yahoo's, take down a few different types and manufacture of bullets off the shelf and start measuring them with a comparator. We all know that bullets vary a good bit from base to tip. But they are SUPPOSED to be the same when measured from base to ogive. That's why we use comparators to measure cartridge length. But, if you get to actually measuring some bullets, you'll find some boxes, of some brands, with a suprising amount of variation from base to ogive. Those bullets don't group as good as consistent ones...
- DAA
