AFTE Store - Contemporary and Historical Black Powder: Physical And Chemical Properties Of Forensic Interest

Properly formulated black gunpowder consists of an intimate, 3-component mixture of sulfur, charcoal and potassium nitrate with nominal percentages of 10%, 15% and 75% respectively. This classic propellant and low order explosive is still used in replica and historic firearms designed for its use. Such firearms are occasional involved in injury incidents and less frequently in crimes consequently the evidentiary aspects of black powder and black powder residues are not nearly so well known by forensic scientists and firearms examiners as those of modern nitrocellulose propellants. Despite a fairly fixed formula for black powder intended for use in firearms, the actual performance of various brands varies considerably when loaded in the same firearm in the same amount and with the same projectile. This is well known to most black powder shooting enthusiasts but the explanation is much less clear. The popular belief is that it has something to do with the source of the charcoal since a variety of woods are used to prepare it but the real reason(s) remain a mystery. This paper provides some data regarding the comparative performance of seven sources of contemporary black powder, the physical and chemical properties of contemporary and historic black powder to include their analyses and comparisons by scanning electron microscopy- energy dispersive x-ray spectrometry (SEM-EDS).