Comparison of Methods for Estimating Range of Fire Based on the Spread of Buckshot Patterns

Abstract

Abstract Three methods of measuring the spread of shotgun pellet patterns for the purpose of estimating the range of fire were applied to a series of 72 00 buckshot patterns test-fired at distances ranging from 3.6 to 10.7 m (12 to 35 ft). The methods applied were (1) the “effective shot dispersion” method of Mattoo and Nabar, (2) a method in which the area of the smallest circumscribed rectangle that will just enclose the pellet pattern is calculated, and (3) an overlay method for determining the radius of the smallest circumscribed circle that will just enclose the pellet pattern. Regression analysis was applied to the resulting measurements of the spread of the pellet patterns. The “effective shot dispersion” was found to give the best fit to a linear function and the best range-of-fire estimates. The area of the pellet patterns was found to be a quadratic function of the range of fire; this measure of pellet pattern spread was also found to have very large shot-to-shot variations. The square root of the area of the pellet pattern was found to be a linear function of the range and to give acceptable range-of-fire estimates.