Ammunition Shelf Life
BY Herschel Smith
Once the ammunition is purchased, where and how it is stored will determine how long it will be viable for its intended use.
Heat and moisture are the two most prevalent enemies of ammunition, followed by chemical contamination.
Temperatures consistently in excess of 150 to 170 degrees Fahrenheit tend to affect the propellant in a negative manner. These temperatures can be reached in car trunks, metal buildings or other uninsulated enclosures subjected to direct sunlight—especially in the southern tiers of the United States.
Anytime ammunition is subjected to continuous exposure to moisture, corrosion is likely to occur, which degrades the performance or disables the usability of the cartridges all together.
Chemical contamination is sometimes the silent killer of ammunition. Although much of today’s quality ammunition is protected by sealant-treated primers and bullets during manufacture, exposure to penetrating oils or cleaning solvents will degrade the sealants over time, thereby neutralizing the priming compound, the propellant or both, rendering the cartridge useless.
Ammoniated solvents used for removing copper from a bore are detrimental to brass cartridge cases, even with minimal exposure. Since brass is 70 percent copper (with the remaining 30 percent being zinc), ammoniated solvents can create a dangerous condition causing the brass to crack without having been fired. This could cause a hazardous pressure release during firing due to the weakened condition of the brass case.
Ammunition storage can be as simple as storing it in a safe area similar in environment to the office within which you work or the home in which you live. Keeping the temperature and humidity levels similar to what is comfortable for you and the family is an easy way to stay well within the range suitable for ammunition storage.
Many individuals who purchase and store quantities of ammunition are served well by storing it in sealed, military-surplus ammunition containers. Kept in a climate controlled, secure location, away from unauthorized personnel, these containers will preserve the ammunition indefinitely.
The reason there is no expiration date on a box of currently manufactured ammunition is because, when stored properly, it is projected to have an unlimited life span.
As an aside, I personally have fired ammunition loaded more than 100 years ago with excellent results. Advancements in primers, powder, cases, projectiles as well as in storage containers and accessories have improved the reliability of ammunition to a point that, properly treated, there is no reason for concern for your ammunition’s longevity.
Use of a sealed container (like a safe) along with desiccant would also help.