Sectional density (SD) is a firearms term related to ammunition. According to gun writer Matthew Boyd, sectional density is "the diameter to weight ratio of a bullet. Calculated by dividing the bullet's weight in pounds by its diameter in inches. Sectional density is important because, all other factors being equal, the higher the SD the better the penetration of the bullet."
Bibliography - Further Reading
- ↑ Boyd, Matthew J., "Basic firearms Terminology Defined." Guns and Shooting Online - Chuck Hawks.com, 2012. Accessed February 19, 2015