You realize that this dimension is pointless without a bullet seated in the neck? You could have a neck that is too thick and it would still show the correct dimension prior to seating a bullet.
Lets try and clear up your issue shall we?
1. A sized case fits into the chamber and drops free.
2. A sized case allows the bolt to lock up properly.
If those two statements are correct then the issue is not in your brass. If these statements are not true then the first thing I'd do is to run the sizing die in a little bit to try to shorten the case and then try steps 1 and 2 again. Repeat until the brass fits the chamber properly.
Once you have the case fitting the chamber properly then we move on to bullet seating. If you have it, a Chamber All gauge is the quickest and most accurate way to get the seating depth correct.
You have already seen markings on the bullet from the lands. Just shorten the loaded length till those do not appear. Don't forget that different bullets will have different shapes and so interface with the rifling at different lengths.
With a bullet seated and lightly crimped, my previous measurements in earlier posts shows 0.332" to 0.333". Here's a couple pics.
1. Cases can fit in the chamber and drop free. A couple cases needs a light tap to make them fall out. All cases are trimmed to the exact same length.
2. Yes. A bolt will close and lockup with an empty case in the chamber as well as extract cleanly.
Yup, I'm aware that different bullets (even from the same batch) will have variances in the shape and OGIVE length. This I learned from loading my 308 stuff. I'm not entirely new to reloading which is why this dilemma is giving me gray hairs. I would have to shorten my ammo to roughly 1.468" to the OGIVE to clear the lands.
I just went and remeasured my COAL on my loads. I was off on my original measurement notes. My 155gr AMAX will be 2.092", my 155gr SMK will be 2.052" and 168gr SMK at 2.063". It doesn't bother me if the ammo is short vs long. I just want to be sure that I'm not creating an overpressure situation esp. when I compare my OAL measurements to that of the Hornady, Sierra and even Hodgdon load data. Going from 2.220" to 2.092" for 155gr AMAX and from 2.105" to 2.050" for 155gr SMK.
Has anyone loaded 155gr AMAX or SMK here and would care to mention their OAL just for reference?
Tomorrow I'm going to try the poor-man's paraffin wax chamber cast since I don't have immediate access to cerrosafe and hopefully I can get some general idea of my chamber measurements. Going from my reloading experience and seeing that all my case dimensions are sound, I've got a gut feeling that my barrel isn't up to spec but we'll see.
FYI, some background info on my thinking ability, I've worked in IT for the last 12 yrs, computers for 20+yrs (yeah computer geek) and have two engineering backgrounds, one of which I've graduated with honors, Civil engineering being one of them and I have also done my share of woodworking/cabinetry so I'm generally pretty adept at problem solving or with measurements and simple displacement theories ie, I know if I stick a .308 diameter object into a 0.333" neck sized case, the thickness of the walls of the case will cause that 0.333" to increase in diameter. Hence why this little issue is driving me knuts. Sorry, don't mean to sound callous, just frustrated is all.
My factory ammo should be here by Thursday, that should be a bit of a litmus test. If they chamber cleanly, then we know it's something I'm doing wrong. Damn, maybe I shudda stuck to 223. This 300BLK is giving me a fracking headache.
