A quantitative comparison of smokeless measurements

Area of Science:

• Analytical Chemistry
• Forensic Science
• Materials Science

Background:

• Accurate quantification of propellant and stabilizer additives in smokeless gunpowder is crucial for forensic investigations and military munitions.
• The National Institute of Standards and Technology (NIST) conducted an international measurement comparison to evaluate current analytical practices.

Purpose of the Study:

• To assess the state-of-the-practice for measuring additives in smokeless gunpowder.
• To identify potential biases and uncertainties in the quantitative and qualitative determination of key components.

Main Methods:

• An international measurement comparison involving five participants reporting on two handgun reloading powders.
• Analysis of key additives including nitroglycerin (NG), ethyl centralite (EC), diphenylamine (DPA), and N-nitrosodiphenylamine (NnDPA).
• Evaluation of reported measurement uncertainties and identification of method-specific calibration biases.

Main Results:

• All five participants reported values for NG, EC, DPA, and NnDPA; some also reported stabilizer decomposition products.
• Nitroglycerin (NG) exhibited greater susceptibility to method-specific calibration biases compared to stabilizer additives.
• One participant's results were strongly biased, while the other four showed concordant measurements with relative ranges of 5-10%.

Conclusions:

• Significant variations exist in the accuracy and consistency of smokeless gunpowder additive measurements.
• Method-specific calibration biases, particularly for unstable components like NG, affect measurement reliability.
• Inconsistent reporting of measurement variance components among participants highlights a need for standardized uncertainty evaluation.