Mr. Nicol. Yes. My opinion would be based upon the finding of families of lines that would be of the order of two to four fine striations on the burr that I referred to. For a stronger identification, I would want a larger group, I would want perhaps five or six in a given area, all matching in terms of contour as well as position. But this I did not find. And so for that reason, I would not want to express this as a positive finding. However, I would not want to be misunderstood or suggest that this could not have come from that particular gun.
Mr. Eisenberg. Now, you say burr. This is a burr in the barrel of the rifle which produced——
Mr. Nicol. No, I believe it is the result of a displacement of metal as the land impresses into the jacket material, and actually machines up a burr along here on the driving edge.
Mr. Eisenberg. So is there an extrusion on—on the rifle barrel which would produce that?
Mr. Nicol. It may have been true at one time. It appeared at some point in the passage through the barrel, this portion of the jacket curled up and subsequently before it left the barrel was touched by the rifling, so that it is now flat and even. When I refer to it as a burr, it is not raised up. It is even with the rest of this surface. But you can see the definite outline of that burr at the land edge.
(At this point the Chairman entered the hearing room.)
Mr. Eisenberg. Now, would this be caused by an extrusion in the barrel or a concavity in the barrel?
Mr. Nicol. It is probably the result of erosion back at the chamber, back at the rear of the barrel, along the land edge here, and then as the bullet gets to the end of the barrel, pressures decrease, so erosion also decreases, and therefore there is still rifling enough left to press this down and make some impression on the projectile itself.
Mr. Eisenberg. And does this lie within a land impression, or the edge of a land impression?
Mr. Nicol. It would be actually in the groove impression.