EVALUATING FABRIC DAMAGE 
DUE TO A CONTACT GUNSHOT  

Melissa M. Tan, Department of Chemistry,  Florida State University, Tallahassee, FL 32306     

H. Dale Nute, PhD, School of Criminology and Criminal Justice,  Florida State University, Tallahassee, FL 32306-1127   

 

ABSTRACT

Examination of damage to clothing fabric from a contact gunshot yields two types of information:
    a) it contributes to the classification of the damage as being due to a gunshot; and,
    b) it contributes to the reconstruction of the distance and angle of the firearm with respect to the
        victim.

The objective of this paper is to demonstrate the complexity of fabric damage analysis due to the variety of factors involved and their interaction.

The factors studied included: the characteristics of the weapon/ammunition combination, the construction of the fabric and the orientation/distance of the weapon to the cloth.

These factors were analyzed using a model that provides three explanations for the cause of fabric damage: the bullet itself, forward gases and reflected gases. Traditionally, the experimental design for analyzing gunshot fabric damage has been limited to arbitrary variations of the weapon used, barrel-to-target distance, angle, and sometimes fabric construction. In this study, we attempted to correlate the nature of the fabric damage to the nature of the force causing the damage.  

INTRODUCTION

We posited that there are three basic causes of fabric damage in a contact shot.
 

POSITS  

  1. Fabric damage is caused by the projectile, forward gases and reflected gases
  2. The fabric structure determines the nature of the damage to the fabric
  3. The weapon type, muzzle-to-target distance, ammunition, and barrel-to-target angle determine the nature and extent of damage to the fabric
  4. The actual damage is due to a combination of these factors

 

 
The first cause is the projectile itself. This isolated effect can be demonstrated when the target is shot from a sufficient distance that the forward moving gases have expanded to the point that their pressure is inadequate to rip the cloth.

The second cause is the forward moving gases propelling the projectile. This isolated effect can be demonstrated by placing the weapon at a 180 degree angle on the target. A stellate tear will result from the force of the gases expanding along the fabric.

The final cause is the projectile plus reflected gases. This effect can be demonstrated when the target is shot with no space between the barrel of the gun and the target. In this instance, the forward moving gases will enter the hole cut by the projectile, and expand forwards against the flesh and backwards against the fabric. The weaker fabric gives way and rips.

The pattern of the damage depends on the relative strength of the fabric with the most damage occurring in the direction of the weakest yarns. Fabric strength along a given direction is determined by the size and strength of the yarn in that direction, the interlock pattern, and the number of yarns.
 
 

ASSUMPTIONS  

  1. Damage by gases will depend on the bursting strength of the fabric
  2. Bursting strength of the fabric depends on a combination of factors including:

  3.    fabric weight   
       fabric construction type 
       yarn size 
       yarn type 
       fiber type 
  4. The deposition of visible soot / smoke discoloration is indicative of a substantial amount of gases impacting the cloth

 
 

DISCUSSION

Classification of the cause of fabric damage is based on the shape of the tear pattern, the orientation of the tear damage and the edges of the tear. The damage varies depending on the type of weapon causing the damage. The damage is recognized to be different for sharp weapons, such as a knife, versus a blunt object versus that due to a projectile from a firearm. However, within the classification of "firearm-caused" damage, there also is some variation, particularly at close ranges and contact.

The shape of the tear pattern for a particular firearm-ammunition combination varies according to the distance of the muzzle from the fabric, the angle of the barrel with respect to the fabric, and the nature of the fabric itself. The shape of the tear pattern includes the relative lengths of the intersecting tears.

The orientation of the tear damage with respect to the fabric structure varies according to the nature of the fabric. The edges of the tear show varied amounts of raveling and missing yarns according to the distance and nature of the fabric.

All of these factors must be considered when classifying fabric damage as due to a gunshot.  

 

MATERIALS AND METHODS

 

Reconstruction information about distance and angle of the firearm is based on quantitative analyses of the variables used to classify the damage as a contact shot. The factors that create the variations include: distance and angle of the muzzle from the body, caliber and type of powder, type of firearm used, and nature of the fabric. In this study, we varied each of these parameters individually, keeping the other factors constant. 

All tests were performed with at least three shots each. 

Muslin was the standard fabric used to test the angle, distance, and type of firearm. The piece of muslin was loosely tucked around a block of ordnance gelatin mounted on a shot box. 

The muzzle distances tested were -1/8", 0", 1/8", 1/4;", 1/2;", 1", and 2". 

The barrel-to-target angles tested were 180 degrees, 90 degrees, 45 degrees, and 30 degrees. 

Weapons used were a .22 cal., .357 cal., .45 cal., and .38 cal. revolver, a .25 cal., .32 cal., .380 cal., .40 cal. and 9 mm  semi-automatic pistol, a .22 cal. and .30 cal. rifle, and .410 cal. and 12 gauge shotgun. 

Fabric type, type of weave, and fabric density, all play a major role in damage characteristics. Fabrics tested include: twill, denim, plain tight, plain loose, unbalanced plain, jersey knit, pique knit, flannel, and vinyl. 

All the fabrics were tested using the standard conditions of a .38 caliber revolver at 1/8"and 90 degrees. 
 

 

 
 
 

 
 

 

   

VARIABLES TESTED

FACTOR

STANDARD

VARIATIONS

Weapon

.38 caliber  semi-automatic pistol

.22 caliber revolver .22 caliber rifle .32 caliber pistol 9 mm pistol .357 revolver .38 revolver .40 pistol .45 revolver .45 pistol

Barrel-to-Target  Angle

90 degrees

45 degrees 35 degrees 180 degrees

Muzzle -to-Target Distance

1/8 inch

-1/8 inch 0 inch 1/4 inch 1/2 inch 1 inch 2 inches 7 inches

Fabric

Plain Weave (muslin)

Plain Unbalanced Weave Twill Weave Weft Knit (Jersey) Warp Knit Knit, Double Cloth Non-woven (vinyl)

   

RESULTS

MUZZLE-TARGET DISTANCE - Produces a spectrum of damage type
Chart shows the correlation as well as the relationship with damage to body.

BARREL-TARGET ANGLE - Changes shape of tear in woven fabrics

FABRIC TYPE - Determines shape of tear
 

WOVEN - tears are along yarn directions
 

PLAIN - longer tear determined by yarn strength

PLAIN, UNBALANCED - pronounced longer tears across weaker yarns

TWILL - pronounced unbalanced tears
 

KNIT - Tears are along interlocking directions but more ragged edges than woven
 

DOUBLE KNIT - interlocking directions obvious

WARP KNITS - ragged but interlocking directions apparent

JERSEY (WEFT) - ragged, little indication of directionality
 

NON-WOVEN - Tears are irregular with no directionality
 

INCONCLUSIVE RESULTS -

Weapon Caliber - In general, the larger the caliber, the greater the damage, however,  the .22 caliber was the only one for which the ammunition could be held constant and it does not produce enough gas to test.

Weapon Characteristics - It appears that the semi-automatic contains the gas better than a revolver and thus causes more damage, all other factors being equal, but all other factors could not be held equal.

FACTORS NOT TESTED -
Powder Load
Fabric Weight
Yarn Characteristics
Fiber Characteristics

     

Force Considerations  

  1. Projectile Only
  2. Projectile Plus Forward Gases
  3. Projectile Plus Reflected Gases
  4. Projectile plus Forward Gases plus Reflected Gases
  5. Forward Gases Only
  6.  

  The force considerations were evaluated by varying the muzzle-target distance and the arrangement of the target cloth with respect to the gelatin block and the angle of the weapon barrel to the target cloth. MUZZLE - TARGET DISTANCE .40 caliber, muslin cloth, 90 deg angle Photos are taken at the same distance so that features are comparable in size.  

    BARREL - TARGET ANGLE .38 caliber, muslin cloth, 1/8 in distance  Photos are taken at the same distance so that features are comparable in size.  

 
 
 
 
 

     

Weapon Considerations  

  1. Weapon Caliber
  2. Powder Load
  3. Muzzle-to-Target Distance
  4. Barrel-to-Target Angle
  5.  

 

CALIBER VARIATION

90 deg angle, 1/8 in distance, muslin cloth Photos are taken at the same distance so that features are comparable in size.    

   

Fabric Considerations  

  1. Fabric Type
  2. Weave/Knit Type
  3. Yarn Count
  4. Yarn Type
  5. Yarn Size
  6. Fiber Type

  The primary fabric consideration tested was the fabric type -- yarn construction versus non-yarn construction -- and variations within the weave and knit types. FABRIC TYPE 90 deg angle, .38 caliber, 1/8 in distance Photos are taken at the same distance so that features are comparable in size.  

WOVEN - PLAIN

WOVEN - PLAIN UNBALANCED

WOVEN - TWILL

NON-WOVEN

KNIT - WEFT

KNIT - WARP

KNIT - DOUBLE CLOTH  

 

     

 CONCLUSIONS

The shape and extent of the tearing varies with respect to each of the factors tested.

Different combinations of factors may produce the same type damage.

Drawing a conclusion as to distance and/or angle of a contact shot therefore requires assessing the totality of the variables and in casework requires testing of the same type fabric using the same weapon and ammunition.
 

ACKNOWLEGEMENTS

We would like to thank the following people for their contributions to this research project:
Dr. Kay Grise and Ms. Amy Fox for assistance and advice in fabric testing techniques;
Ray and Laura Bedard for the loan of some firearms;
Enos and Patt Kerr for the loan of some firearms;
Ms. Ginny Ellsworth for supplying some of the more esoteric fabrics.