Re: Question-Bullet Comparators
neither one will. and your seating die wont contact the bullet at the same location as the comparators. what the two comparators are giving you is a measurement to a "datum point". regardless of the measurement to the datum point, your bullet is still touching the lands with both. what you have to do is pick one, then you "set" your die so that when you seat a bullet in a case and then measure said loaded case (with the comparator of your choice) the measurement is the same one you got when you measured your chamber.
the problem stems from the fact that the ogive is not the same on every kind of bullet, thus it is not possible to make a comparator that actually tells you where your lands are. so what you get is a somewhat random sized hole that varies by manufacturer and measures at some point between the tip and the shank of the bullet. but it makes no difference because you are using the same random point every time you measure the loaded round.
to make things interesting you will need to repeat the process every time you get a new batch of bullets (even if they are the same make as your previous ones) because every batch of bullets is slightly different. if you take a 168gr smk for example, then grab a 168gr nosler j4, the ogive profile is different. this means that the location along the bullets length where they touch the lands is different, thus the OAL will be different when both are touching the lands. and because your seating die also uses a random point along the ogive to seat the bullets, you will have to reset it for both bullets to get them both to just touch the lands.
if you want to know the actual distance from the bolt face to the lands, then you will need to get a chamber cast made. but this information is nearly useless because you wont be able to find a comparator that will measure to the same point on the bullet nor a seating die that will seat at the same point.
clear as mud right?
I am using a Hornady Lock-N-Load OAL gauge and the associated 30 cal. bullet comparator. After measuring the OAL many times to get a good average, I tried doing the same thing using a Sinclair comparator. All of my readings were consistently off by .095. I then measured how deep the bullet fit into each comparator and it turns out that the same bullet sits .095 deeper in the Sinclair comparator. So, which measurement do I use to set up my die and why? I'm sure there is something obvious that I am missing so hopefully the wealth of experience here will set me straight! 
Thanks in advance for any help you guys can provide to get me started off on the right foot!
