An investigation into pellet dispersion ballistics

Area of Science:

• Ballistics
• Forensic Science
• Physics

Background:

• Existing pellet dispersion models rely on statistical analysis of target patterns, neglecting the underlying physical processes.
• A theoretical framework for pellet dispersion phenomena is underdeveloped.
• Understanding pellet dispersion is crucial for forensic applications like crime scene reconstruction.

Purpose of the Study:

• To develop a general theoretical model for pellet dispersion.
• To investigate the physical process of dispersion based on momentum transfer.
• To establish a quantifiable measure of dispersion capability.

Main Methods:

• Developed a theoretical model for radial velocity distribution of pellets.
• Analyzed momentum transfer from undispersed shot mass to dispersed pellets.
• Introduced the 'Dispersion Index' (DI) as a characteristic measure of dispersion capability.

Main Results:

• The ratio 2u/v0 (where u is RMS radial velocity and v0 is muzzle velocity) was found to be constant for a given gun-ammunition combination, termed 'Dispersion Index' (DI).
• The model accurately predicts pellet distribution and 'Effective Shot Dispersion' (ESD).
• A relationship between ESD, firing distance, air resistance, and gravity was established, showing DI controls dispersion.

Conclusions:

• The developed theoretical model provides a versatile explanation for pellet dispersion.
• The 'Dispersion Index' (DI) is a key parameter controlling dispersion at a given distance.
• The model's ability to explain dependencies on firing distance and gun-ammunition parameters enhances its utility in forensic investigations.