I've seen partial head separations, but I have never seen them repeat exactly each time they occur. Some will be longer and some will be shorter. When you investigate with the probe, you find thinning around much or all of the circumference.
There is obviously something going and it needs to be identified and corrected before going further. That case separation can and does occur does not mean that's what's happening to this rifle. It could be the problem, but there is no real way to check over the internet.