Wayspr, it's been a while since I've used a Hornady OAL gauge and Comparator (since I'm not really convinced this is a valid technique), but isn't the 1.007" a calibrated distance per each comparator that assumes the distance from the end of the comparator to the ogive IN the comparator?

So with this tool, what you actually measured, assuming that your calipers were zeroed on dead close, was the distance from the base of your case to the end of the comparator (or at least to the bottom of the SLOT in the comparator).

Then, if you assume that the comparator bushing ID's match your land ID PERFECTLY, then you can subtract the 'calibrated length' from your measurement and get your distance from the case base to the ogive.

That is why you got something around 2.935" instead of 3.340" as listed in your manual. You measured to the Ogive, not the tip. The 3.3xx number for COAL measures the entire loaded cartridge length, but for different bullet profiles and different rifles, COAL is irrelevant. The 2.935" was not the COAL (not analogous to the 3.340" COAL), but instead is the distance from the case base to where the ogive will touch the lands. So if you measure that 2.935" with the comparator, your COAL might actually be 3.340" with that bullet.

WHY THIS IS IMPORTANT:

Different bullets have different profiles. Bullet jump is typically far more important than COAL, so if you have a damaged tipped vs. a pristine tipped bullet, but seat to the same COAL, you might end up being several thousandths difference in jump, and a rifle will know the difference between an extra 0.015" jump a lot more than it will notice a difference in 0.015" extra tip hanging out front.

So basically, you can measure your bullet seating span with ANY bullet, and it will NEVER CHANGE FOR ANY BULLET. It's matched to your rifle. So if your rifle has 2.935" from the bolt face to the lands minimum ID (i.e. end of your throat), it will be 2.935" for any bullet, no matter what. BUT, for a long profile VLD, that 2.935" chamber span might correspond to 3.57", whereas with a heavy round nose it might only correspond to 3.32" (exaggeration).

There's also a problem with the Hornady OAL gauge, such that it needs to be zeroed and a calibration reference subtracted, but that's an entirely different can of worms.

At any rate: To properly use the Hornady Comparator and OAL gauge. Insert the modified case with a bullet in question, and determine your maximum seating length for that bullet. Pull it out, and measure using the comparator. Subtract the calibration length for the comparator from your measurement, then subtract your desired bullet jump length (the 0.03" you referred to). This number will be your ogive depth for THAT PARTICULAR RIFLE.

Then, without moving the bullet, measure your COAL, and subtract that same bullet jump length. This will be your COAL for THAT PARTICULAR BULLET.

So then when you switch to a new bullet, you can set your dies to seat to that same comparator length and never have to use your Hornady OAL gauge ever again. That WILL correspond to a different COAL, but it will seat your bullet to the same bullet jump that you want.

Clear as mud?