4seventy
On inspection of the cases head on the cartridge that dropped the primer there is a slight mark from the extractor groove in the bolt face but certainly no more than on any other cartridge that I reload for and I reload for 7 different cartridges. On looking at the batch of ammo that was faulty some of the cases have a soot ring appearing around the primer although the primer didnt drop out.
There is no discernable marks on the head or around the webbing area of the cases although the primers seem to be slightly flattened with a slight cratering around the firing pin indentations.
The cases that have soot marks around the primers also have a color change at the throat of the cartridge which looks a little like annealing marks. This may have been caused by a hot chamber.????

I measured the case head diameter of the cases that did not drop primers and than all measured .528" the Head diameter on the dropped primer cases measured .530" the primer pockets on the dropped cases measured .212" The SAAMI spec lists a maximum of .210" so there is obviously some pressure at play here. I do not have unfired cases to measure against at the moment but the reloaded ammo I have measure similar to the cases that havent dropped the primers.

As an aside a bit of information for those that have a 416Ruger and like to reload I have noticed when reloading the cases need to have a primer pocket uniformer used on them to enable the primer to fully seat(Fed 215) some seat all the way some wont.