Exploring the Science Behind Epoxy Encased Live Ammunition Discharge
By Roderick Kabel
In recent times, the internet has been abuzz with awe-inspiring images of river tables adorned with various ammunition casings encased within epoxy. While most creators opt for empty brass casings to achieve this aesthetic, some dare to incorporate "live" ammunition, believing it enhances the visual appeal and wow-factor. However, the potential dangers associated with live rounds submerged in epoxy have largely remained unexplored.
At WiseBond®, safety is paramount. We advocate for the removal of primers or gunpowder (dummy rounds) before encapsulating ammunition in epoxy, as a precautionary measure to mitigate risks. Not only does this practice ensure the safety of the creator and those around the finished project, but it also maintains the project's allure without compromising on safety.
A recent incident involving one of our WiseBond® influencers, a seasoned epoxy artisan, emphasizes the risks associated with live ammunition. Commissioned to craft display cases for an ammunition manufacturer, the influencer encountered a catastrophic event following an epoxy pour conducted in the evening. Fortunately, the incident occurred in the influencer's absence, sparing them from potential harm.
Subsequent examination of the display cases revealed that four ammunition rounds detonated within the epoxy casting, including two 10mm rounds, one .380acp, and one 9mm round, while others remained inert.
This alarming discovery prompted a comprehensive investigation here at WiseBond® into the underlying causes. The fact that four rounds detonated out of numerous other rounds, is ONE too many!
Our initial speculation centered on the possibility of epoxy-induced pressure triggering primer ignition during the exothermic cooldown phase as the epoxy begins to shrink. However, further analysis revealed that primer ignition necessitates direct impact from a firing pin, a condition not met in this scenario.
The discussion then shifted to the possibility of ammunition self-igniting due to ambient heat. While ammunition may "cook off" when exposed to high temperatures, such as those generated by a fire. Typically, gunpowder requires temperatures between 801–867 °F to ignite.
Contrary to popular belief, the interior of a vehicle does not reach temperatures conducive to ammunition cooking off, as evidenced by veterans' experiences in hot desert climates.
It's important to note that ammunition in hot vehicles and even when stored in boxes, there is air circulation, whether active or passive, which helps to cool the primer, preventing ignition. It's crucial to recognize that deep pour epoxy does not contain air pockets, thus eliminating any cooling effect on the primer.
Central to our investigation is an understanding of the mechanics of a primer, comprising essential components such as the primer cup, primer mixture (an “impact sensitive explosive”), protective foil paper, and anvil. The primer's function hinges on the compression of the primer cup, which, upon impact, ignites the primer mixture compound and initiates the firing sequence.
Considering the ignition point of the primer mixture is a much lower threshold than gunpowder, the exothermic reaction of epoxy can potentially provide sufficient heat to ignite. Primer mixture compound used in most modern primers is called DDNP (diazodinitrophenol). Depending on the exact composition of the primer compound, temps above 150F can be enough to cause it to detonate. The exothermic reaction of epoxy can generate temperatures ranging from 140-165 °F, well within the range necessary for the primer mixture to ignite.
In summary, our final conclusion hinges on the lack of air within the epoxy, heightening the potential for ignition. Without air to dissipate heat and cool the primer, the primer mixture was able to reach a temperature conducive to ignition during the exothermic reaction of the epoxy. This resulted in ignition, leading to the expulsion of the bullet encased within the epoxy.
Special thanks to Cody over at Shadow Systems based in Plano, Texas, for assisting us with a greater understanding of ammunition and primers. Shadow Systems is a Made in America designer and manufacturer of premium firearms and firearms parts. Please give them a look at www.shadowsystemscorp.com and their YouTube channel @ShadowSystemsCorp.
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