Mr. Eisenberg. The firing-pin impression. And what about the area of the primer around the firing-pin impression?
Mr. Cunningham. Yes, sir.
Mr. Eisenberg. In other words, each of these three areas—the brass, the primer, and the firing-pin impression—carries individually characteristic microscopic marks which would be the basis of identification?
Mr. Cunningham. Yes, you cannot make a flat statement.
Mr. Eisenberg. No; in this case.
Mr. Cunningham. In this particular case, I knew at the time I was examining it, all of the firing-pin impressions were excellent, and some portions of the breech-face marks were. But you cannot say they will mark in exactly the same place, due to the fact that these cases will mark in different areas, they are different cartridges, they have been fired at a different time. You will get good areas, and then in another area your marks will not be sufficient. In other words, it is just the way the cartridge case was driven back at the time of the explosion in the primer, and the bullet is fired.
They can hit slightly different, hit deeper on one side, be lighter on the other. When a primer is set in a little bit deeper, it will not pick up these marks on the primer part, whereas the firing-pin impression can be excellent—one portion of the case will be excellent. But each one is a different examination. And many times they will mark in different places.
Mr. Eisenberg. Could you show us the next photograph?
Mr. Cunningham. Yes, sir. This is Commission document No. 597. This is a photograph, photomicrograph, rather, of the breech face marks on two cartridge cases. The one on the left is C-49, which is our number C-49, and the one on the right of the hairline is a test cartridge case from this revolver.
Mr. Eisenberg. What is the magnification?