This is important as a matter of record and, of course, is routine procedure in most laboratories. The first thing to do is to take a good photograph, preferably enlarged several times, of the area upon which the number should appear, in order to show the exact condition that existed before any treatment was made. 6, p 479 (1961).įailing to find any useful information by a careful inspection of the gun, one may then resort to a restoration of the number. *For information on the location of serial numbers on various automatic pistols see The Identification of Pistols by Serial Numbers and Other Markings, by V. The manufacturer's identification number must not be confused with the serial number. The serial number is on the lower right side of the frame (and only there). The manufacturer (High Standard Co.) puts his identification number and the statement of model and caliber on the left side of the barrel. The model number is present on both sides of the grips. One must be familiar with the practice of the manufacturer of that make of gun.Ī knowledge of the place where a serial number may usually be found is, of course, of great assistance.* Also, one must not confuse a manufacturer's number with the serial number. So, instead of being helpful in interpreting a serial number that comes out faintly upon etching it may add to the confusion. Oftentimes, on the other hand, the number on the barrel may bear no relation to the serial number, so one must not assume that because a number is there it necessarily is a part of a serial number. In automatics of foreign make the last three digits of the serial number are often placed on the barrel, but seldom does the entire number appear there-unless it is a two or.three-digit number. Disassembly of the gun may reveal serial numbers in several places, depending on the make of the gun. If this fails, the inside of the grip plates may show a pencilled serial number. Many cases can be solved quite simply, particularly for some makes of revolvers, by removing the grip plates and examining the frame where the number may be stamped. Often times with suitable illumination and some magnification the number can be discovered and deciphered, particularly if the surface is wetted. When a gun is brought to the laboratory for the restoration of a serial number the first thing to do is to examine the gun both inside and out to see whether any such number is present. If, however, the removal of surface metal is continued until all the metal in the zone of strain is removed the numbers cannot then be restored. This is because the act of filing or grinding is usually stopped as soon as the numbers just disappear, thus leaving some of the zone of strained metal. These unequal rates of solution of strained and unstrained metal make it possible, in many cases, to „bring out" numbers that have been removed by filing or grinding. It is a fact well known to metallurgists and metallographers that metal treated with certain etching reagents will react (dissolve) at a different rate in areas which are under strain than in areas which are not under strain. There will thus be a zone of strain immediately surrounding each digit and extending a short distance below the limit of penetration of the die. In either case, the stamping of these numbers disturbs the crystals of the metal and puts them under a strain which is permanent. The principles involved are as follows: When the numbers are stamped in by a hard steel die, the die is struck a sharp blow to make each digit sink into the metal to the proper depth, or the die may be forced into the metal under pressure. The practice of removing serial numbers is not as popular among criminals as it once was as they have now learned that their efforts are futile.įortunately, when occasion demands, there are methods whereby numbers which have been removed can often be restored to such an extent that they can be read and photographed, provided the filing or grinding is not too deep. The serial numbers on stolen guns are also frequently removed. Occasionally guns found at or near the scene of a shooting or taken from a suspect will have had the serial number removed either by filing or, less frequently, by grinding.
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