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Lastly, I've never really observed pressure signs. I've not seen pocket issues or neck splitting or splitting at the bottom of the case.
Checking thickness on the Lapua brass it is .0015 thick. Some of my other once fired factory brass is .0015 or .0012.
-JD-
Yes you did, you just haven't recognized them. Just because your gun doesn't blow up in your face doesn't mean you're "good".
Neck splitting or primer pockets going loose or blowing primers on the first shot is a sign that you're REALLY fucking things up. Case head separation is not always a pressure problem as it is a stretching/resizing problem. Either way, if you experience any of those 3 things, you're doing it COMPLETELY wrong.
Now, pressure signs includes, but is not limited to: Shiny marks on case head, flattened primers, cratered primers, primers or brass flowing, peirced primers, popped primers, case bulging, splits, cracks, separations, ejector/extractor marks, sticky bolt.
Your brass exhibits the following: Shiny marks on case head, brass flowing/ejector marks, and primer cratering/flowing.
Your loads are too hot. You're going to wreck your Lapua brass in way fewer firings than you should.
Look at how the machining marks (rings on the bolt face) are stamped into your primers and brass. The very obvious ejector marks-- Your pressure is so high that you're deforming your brass and it's trying to shove through your ejector hole, then when you cam the bolt open you shear a bit of brass off of the nipple that was extruded into your ejector hole.
Now, as to what is causing it? Hard telling. When you're shoot near max loads and getting pressure signs, can't really tell. Back off until you don't see any of the signs listed above, see what charge you're dealing with and chrono it and see what kind of velocity you're getting. Then you can see how jacked things are (if at all). Or, like others have said (and even easier), try some FGMM or other quality factory ammo.
The scrape on the mouth/neck area is from extraction. It's dragging somewhere on the inside of the front ring of the receiver. Maybe hitting a lug recess or something.
edit to add: looks like you also have some gas blow-by with the primers. The craters aren't that worrisome since it's a stock bolt face and firing pin (mine does it too, regardless of load). Check your bolt face, you might have some pitting from the gas flow.
