There's a lot that is fundamentally wrong with what you're doing OP; I say this lovingly.
--- Always open to feedback! Much appreciated.
1.) Those aren't comparators. That's a caliper. Comparators attach to calipers to give you relative measurements. Get a set of OAL and headspace comparators.
--- Edit*** The OAL gauge** is out of frame, I was using the calipers to show the potential OAL the chamber was allowing.
2.) Once you get the OAL comparator, measure your depth relative to the lands using the BTO vs. OAL (like you're doing now). Measuring OAL on a OTM/HP bullet will never be consistent session to session, and more importantly lot to lot.
---Good point, I've generally always used OAL enstead of BTO. In the past, I've had trouble getting consistent BTO measurements thus never had much confidence in them, I do have the equipment. I'll give it another go.
I bet that gun shoots great some days, and not as great others; it's probably because you're varying your seating depth (relative to the lands, where it matters) by as much as ~.010-.015 between sessions, and god only knows between different lots of bullets.
---Question - Assuming I'm using the same lot of bullets and seating die adjustments have not been made I should not have any variation in the seating depth, whether the seating die was set from a OAL or BTO measurement correct?
--- Question 2 - Is there a correlation between the jump distance and carbon ring set in time?
3.) Once you get the headspace/bump comparator, start using FL dies. That neck sizing stuff is stupid, and will result in you having difficulty chambering brass every single time. You need to bump the shoulders ~.002 back. This is very close to neck sizing, but will afford you the benefit of sizing your case enough to chamber without any drama.
---Will look into this, thanks!
4.) If you aren't using a micrometer seater, start doing that.
--- I've got one
5.) Carbon rings form in the throat, but unless you've got way too little neck wall clearance (for a PRS rifle like you're shooting), it shouldn't prevent you from cambering a round after 250 down the tube. Just basic cleaning should also take care of them...they aren't as big a deal as the internet makes out, unless you just don't clean the rifle ever. Use something like BoreTech and a good bronze brush...you'll never even see a carbon ring with your Borescope if you do this.
---I understand the concept of the carbon ring, I just don't understand the geometry of location of the one that I had. I probably should have waited until the borescope came in to get a better understanding of what was going on internally. It strikes me as odd that I would be able to get a case in the the chamber and push a bullet to nearly 2.9" with my compatater but would not be able to chamber a round that would be taking up less internal volume.
Thanks again for the feedback to all. I'm stoked to have an outlet of knowledge I can reach out to and get helpful answers as opposed to chair trolls sharp shooting.
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