and make a determination for himself concerning whether a given cartridge case had been fired in a given weapon.?

A. In that connection that person could look through the microscope. He may or may not see these individual characteristics which are present, because he does not know what to look for in the first place, and, secondly, they are of such a nature that you have to mentally sort them out in your mind going back and forth between one area and the other until you form a mental picture of them in a comparison such as this.

If it was a different type of comparison, of parallel marks or something of that nature, then he could see the marks, but in either instance, without having compared hundreds and hundreds of specimens, he would not be able to make any statement as to whether or not they were fired from the same rifle.

Q. Would you say that this is, then, a matter of expert interpretation rather than a point-for-point comparison which a layman could make ?

A. I would say so; yes. I don't think a layman would recognize some of the things on these cartridge cases and some shown in the photographs as actually being significant or not. significant, because there will be things present which have nothing whatsoever to do with the firing of the cartridge case in the gun.

There may be a depression in the primer to begin with, and there are no marks registered at that point as a result of the firing. Unless these things are known to occur, someone may actually arrive at a different conclusion, because of the absence of similar marks.

Q. Now having reference to the specific exhibit before you, which is 559--

A. Yes.

Q. Are all the marks shown in both photographs identical?

A. No.

Q. And could you go into detail on a mark which is not identical to explain why you would get such a result?

A. Well, for instance, between what I have drawn here as circle 4 and circle 5, there is a slanting line from the upper left to the lower right on C-6. This line shows as a white line in the photograph.

On the other side there is a rough, very rough ridge which runs through there, having an entirely different appearance from the relatively sharp line on C-6. The significant part of that mark is the groove in between, rather than the sharp edge of the mark, because the sharp corner could be affected by the hardness of the metal or the irregular surface of the primer and the amount of pressure exerted against it, pressing it back against the face of the bolt, at the time the cartridges were fired. So that you would never expect all the marks on one cartridge case to be identical with all the marks on the other cartridge case.