This was a 830 gr monolithic with 200 grains of Vihtavuori 20N and a CCI 35 primer. Lapua brass.

The three cartridges were for fouling shots, velocity came out at 2130 fps. Anaemic, just foulers.

The one extracted normally. The other two did not extract. Usually, when I open the bolt and nothing comes out, it's a case head separation. The entire case remained in the chamber. Barely a tap from a rod down the muzzle extracted the case.

I do not understand how the case rim escaped from the extractor when the bolt was opened.

It is possible that the primer pockets are loose, this is brass that I use for load development, it may have experienced a couple of hot firings already.

How does the primer back out just that far ? A loose primer pocket with a hot load tends to leave the primer stuck to the bolt face, so when the case ejects, the primer stays behind. There was no high pressure, bolt opened as easily as it closed.