Wadding Material

Demonstrating the rationale for conclusions based on physical comparison carries more weight than a simple statement regarding wadding design. Therefore, availability of a reference standard is necessary for the identification of wadding materials. The reference standard may be from physical reference files maintained in the laboratory or from unfired ammunition seized during an investigation. Consistency of observable physical characteristics and their dimensions are key concerns addressed in the comparison.

If the wadding components are distorted or deformed, it may be necessary to obtain known standards by test firing to provide a better basis for comparison.

The following recommended procedure for examination of wadding material is consistent with the requirements of the Procedural Manual of the Association of Firearm and Tool Mark Examiners (AFTE).

The steps for this procedure are as follows:

1. Perform preliminary procedures.
2. Compare all physical characteristics of the evidence wadding component to the standards of similar manufacture and composition, including these:
   • Color.
   • Dimensions.
     • Measure diameter; use to determine gauge.
     • Measure length.
   • Design (number of petals, composition, shape).
     • Determine composition.
     • Determine number of petals plastic wads only.
     • Describe shape.
   • Shot Size.
     • Determine range of shot sizes as indicated by impressions on wadding material.
3. Disassemble one unfired evidence shotshell for physical comparison of wadding materials, if required and available.
4. Acquire fired standards for comparison, if wadding is deformed and distorted.
5. Identify individual markings (these are unusual when found).

• Compare striated marks (if present) on wadding materials with standards fired from the evidence firearm.

Shot Pellets

Weight

One method of determining shot size is the calculation of average pellet weight. This is the method of choice if deformation has occurred.

The steps for this procedure are as follows:

1. Perform preliminary procedures.
2. Record the total number of pellets received.
3. Determine the composition of the pellets received.
4. Determine the total number of pellets suitable for weighing.
   • Note whether or not all of the pellets appear to be similar. If not, group them accordingly.
5. For each type of pellet present, weigh pellets together for total weight in grains or grams.
6. Divide the total weight of pellets by the total number weighed to obtain an average pellet weight.
7. Determine the shot size based on the average pellet weight of the evidence shot by comparing to a standard table of shot sizes.
8. The weight of evidence pellets can also be directly compared to the weight of standards using the same number of pellets until a similar known weight is obtained.

Dimensions

Deformation and distortion make it difficult to measure the dimensions of pellets, limiting the number of pellets that can be used as a basis for determining shot size.

The steps for this procedure are as follows:

1. Perform preliminary procedures.
2. Determine the total number of pellets received.
3. Determine the composition of the pellets.
4. It may be useful in some cases to enlist the aid of an instrumental chemist in determining the composition of non-lead shot.
5. Determine which pellets are suitable for measuring. For example, determine which pellets roll freely; pellets that roll freely should be measured.
6. Measure and record the diameters of the pellets in hundredths or thousandths of an inch. For small pellets, it is generally appropriate to record three decimal places; for buckshot, two decimal places are appropriate.
7. Determine the shot size of the evidence shot by comparing to a standard table of shot sizes. Note that industry sources indicate shot designated as a certain size may vary up to plus or minus half a shot size.

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