Mr. Nicol. I cannot say that this could not have been produced by another gun.
Mr. Eisenberg. That might have been produced by another gun?
Mr. Nicol. Yes.
Mr. Eisenberg. But it was produced by the same source, whether it was this gun or another gun, three different times?
Mr. Nicol. Correct.
Mr. Eisenberg. Somebody had done one operation, in your opinion, with this cartridge at three different times?
Mr. Nicol. Right.
Mr. Eisenberg. Now, just to set this in context, I have taken the bolt from Commission Exhibit 139, the rifle found on the sixth floor, and could you show the Commission what the extractor is on this bolt?
Mr. Nicol. The extractor is this semicircular piece extending back in the bolt, and its purpose is to withdraw the cartridge from the chamber at the time that the bolt is drawn back. It rides in the extractor groove, which is machined in the head of the cartridge case. At the time that the weapon is loaded, oftentimes this springs around, it first contacts the rim of the cartridge case, and then springs around the rim of the cartridge and produces marks such as these, or marks such as I have illustrated on the three sets.
Mr. Eisenberg. Now, is it possible that the reason the marks were present on this cartridge but not on the other cartridge case—on this cartridge case but not on the other cartridge cases you examined—is because these marks were produced by dry firing as opposed to actual firing?