Unusual improvisation of factory made firearms and
misleading investigation

J K Sinha

[CBI  Bulletin, India. 1994(4)23-24]


 
 

                In recent past, firearms have been extensively used in terrorist activities besides usual criminal cases. Variety of firearms modern as well as obsolete have been used. Firearms are rarely seized, immediately after the commission of the crime. In such cases, the expert is confronted with the task of helping the investigating agency for providing all possible information to lay hands on the probable firearm and the suspect from the available evidentiary clues found at the crime scene or from the victim's body.
     The firearm related evidentiary clues, left behind at the crime scene, are fired cartridges, bullets, pellets , wads, etc. The base markings and the dimensions of fired cartridges reveal the caliber and the type of the firearm used. The class characteristic rifling marks on fired bullets reveal the calibre and the probable make and model of the rifled firearm used. A comprehensive data of class characteristic marks of rifled firearms including obsolete and in obsolation enables the expert to form opinion within reasonable limits. But it poses problems if the firearm involved is an improvised regular factory-made firearm, modified to fire ammunition of calibre other than the original .Neither the base markings on the fired cartridges nor the rifling marks on the fired bullets would reveal the calibre, make and model of the original firearm. In view of increasing use of improvised firearms it becomes essential to seek expert opinion even though the base markings, rifling marks, shape, size,etc., of fired cartridges and bullets are apparently unambiguous for a generalised opinion, usually formed by the investigating officer at the crime scene. The generalised opinion of the investigating officer, in such cases, may result into misleading investigation. Due caution is, therefore, necessary while evaluating class characteristic details and monograms. The present paper describes a criminal case involving unusual improvisation of a regular factory made firearm and likely misleading investigation.
     In the instant case 12 bore fired shotgun cartridges and .303 fired rifle cartridges were recovered from the scene of crime. On examination of .303 fired cartridges it was found that their shapes(FIG. I C) were not in conformity with the shapes of the .303 cartridges fired from regular factory made .303 rifles(FIG. I A). This indicated the probable use of a non standard firearm capable of firing .303 cartridges.


A             B         C
FIG I

     Subsequently two firearms were recovered from the possession of the suspects and sent to the laboratory for linkage. One of the firearms was a .315 Indian ordnance factory manufactured sporting rifle and the other was a double barrel firearm of Belgium make. The double barrel firearm was an obsolete firearm ,a combination of a shotgun and a sporting rifle. The left barrel was a .32-40 sporting rifle and the right barrel was a 12 bore shot gun. Test cartridges were fired from the double barrel firearm and the .315 rifle. On examination and comparison of test and crime cartridges it was found that the 12 bore fired cartridges were fired from the right shotgun barrel of the obsolete double barrel firearm .The test .32-40 rifle cartridges fired from the left barrel showed unusual expansion and split near the mouth. (Fig. I B) This indicated that the chamber of the left barrel was modified and enlarged. But the firing pin marks present on the .32-40 tests and on the .303 crime cartridges were found to be similar in their individual characteristics.

FIG II
.303 crime cartridge           .32-40 test cartridge

     This lead to the conclusion that the .303 fired rifle cartridges recovered from the crime scene had been fired through the left .32-40 rifled barrel of the obsolete double barrel firearm and not from a.303 rifle. This could be possible only if the chamber of the rifled barrel was modified to accommodate .303 rifle cartridges. On examination, it was found that .303 rifle cartridges could easily be loaded in the chamber of the left rifled barrel, originally meant for firing .32-40 rifle cartridges. The .32-40 cartridges are smaller in size compared to .303 rifle cartridges. Tests .303 rifle cartridges were fired through the left barrel of the double barrel firearm .The expansion on the walls of the test .303 fired cartridges confirmed the improvisation of the chamber of the .32-40 rifled barrel. On the other hand, the test .303 fired bullets,as expected, were found to carry clearly demarcated land and groove marks of the right handed .32-40 rifled barrel.

FIG III

     This suggested that only the chamber of the rifled barrel was improvised without modifying the bore. Proper engraving of rifling marks of .32-40 rifled barrel on usual .303 K.F.Mk VII bullet (Fig.III) could be due to insignificant dimensional difference between the .303 jacketed bullet and the .32-40 soft nose bullet and setup during firing. Thus in the present improvised condition, irrespective of the cartridges fired whether .303 or .32-40, the use of locally made firearm would ordinarily appear more probable than improvised factory made firearm. This is especially so because locally made firearms designed to fire rifle cartridges are commonly used in criminal cases in our country. Contrarily, the .303 fired bullets having properly engraved rifling (Fig.III) would suggest the use of a .303 rifle unless elimination on the basis of class characteristics rifling marks is made. In the absence of the involved firearm, both the fired cartridges and fired bullets may lead to erroneous conclusion in ascertaining the calibre and type of the firearm used during the field investigation. Likewise, proof marks, serial number ,writings and monograms regarding calibre, make and model on the recovered firearm ,in such cases, may also be misleading and may pose problem to the investigating officer during field investigation. With the increasing trend of improvisation of uncommon bore factory-made firearms for accommodating and firing easily available cartridges, due caution must be exercised both by forensic scientist and by investigating officer during laboratory examination and field investigation. Hasty conclusions drawn at the crime scene on the basis of apparently looking unambiguous base markings, shape and size of fired cartridges and bullets, at times, may be erroneous. They may mislead the investigation unless they are examined in all aspects preferably by an expert. The possible use of improvised firearm should also be invariably probed while examining and forming opinion .

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