Binders for small-caliber gun primers: understanding gum arabic and exploring possible synthetic replacements

Abstract

Misfiring and hang-firing have been long-term, sporadic problems with 7.62-mm ammunition. These types of problems can cause injury to the shooter or others in the vicinity. This issue is believed to be related to inconsistency of the primer binder gum arabic (GA). A multi-organization project involving USDA Forest Service, Forest Products Laboratory, was put together to work on solving this issue. The project was divided into two phases. Phase I was to understand the properties of GA in its application of holding together the explosives in small-caliber gun primers. Understanding the properties helped to provide improved specifications for this use. Phase II was to use this information to select promising synthetic binders to replace GA for more consistent quality and to avoid dependence on a product that comes from sub-Saharan Africa. After several pellet integrity tests (tumbling, vibrating table, and radial crush), several synthetic binders were recommended as possible replacements for GA for use in primer pellets. However, the recommended binders were never tested in live ammunition. The funding and management for the program was provided by the U.S. Army Joint Munitions Command (JMC), but the champion of this program at JMC was reassigned. The project was deprioritized before the live ammunition testing could be carried out.

Citation

Frihart, C.R.; Beecher, J.F. 2022. Binders for small-caliber gun primers: understanding gum arabic and exploring possible synthetic replacements. General Technical Report FPL-GTR-295. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 64 p. https://doi.org/10.2737/FPL-GTR-295.