denton
Member
Years ago, I started gathering materials for an article on judging pressure by primer flatness. I loaded a batch of cartridges with widely varying charges, marked each primer, fired the cartridges, and then popped the primers out.
Under the microscope, I arranged the primers from least to most flattened. There was no correlation between flatness and powder charge. You can't judge pressure by looking at primers.
Of course, if you have primers falling out, extruding into the firing pin hole, or flowing excessively, those are problems. But short of that, there is so much variation in primer hardness that you can't gauge pressure by primer flatness.
Under the microscope, I arranged the primers from least to most flattened. There was no correlation between flatness and powder charge. You can't judge pressure by looking at primers.
Of course, if you have primers falling out, extruding into the firing pin hole, or flowing excessively, those are problems. But short of that, there is so much variation in primer hardness that you can't gauge pressure by primer flatness.
Last edited: