The Best Long Term Ammo Storage Tips

The US military has strict specifications for the metal ammo cans which house the ammunition itself. Military ammo cans must adhere to strict standards and pass inspection on dozens of requirements that are found in a 56 page inspection manual. Each ammo can is required to be made with cold rolled steel to ASTM A109 or ASTM A568 spec with a zinc phosphate base coat and powder coat finish for superior corrosion resistance. The finish applied to each mil-Spec ammo can must have a minimum surface finish thickness and pass an 80 hour salt spray test. 

The most important part of the ammo can is the latch and rubber gasket. The latch and gasket form the seal that makes the ammo can water and airtight for decades. The ammo can latch and gasket are governed by strict standards and requirements. The latch assembly “shall withstand a pull of 1000 pounds for one minute without failure of the hasp or weld.” The gaskets are required to be made of a synthetic, Grade number 4 rubber material with a special hardness and tensile strength rating that resists extreme pressure, deflection, distortion, and long-term temperature and environmental fluctuations. The requirements of the gasket are very specific, and costly to produce which is one of the key differences between consumer grade ammo cans and military ammo cans. Almost 40% of the manufacturing cost of each can is the gasket. Preserving the integrity of the gasket in the ammo can lids is crucial for long-term moisture protection. The cover assembly is built in such a way to maintain rigidity and ensure uniform pressure on the gasket. I have heard stories from buddies in US Navy Riverine units about an incident where a number of full ammo cans where lost overboard. The cans rested on the riverbed, submerged for years until the river dried out and the ammo cans were found. The ammo in the cans was still dry despite being submerged in the river for a few years. I doubt the career of the individuals responsible for losing the ammo stayed as dry as the ammo once the lot numbers were traced back at the armory.

The wood ammunition crates that ammo cans are shipped inside are also designed in a way to preserve the ammo can gasket. The wood crates are load bearing and prevent the ammo can gasket and lid from having to support the weight of anything stacked on top of the crates. For the ultimate in long-term ammo storage, wood crates look cool and provide additional function and protection. Every piece of the military ammo packaging serves an important purpose in reaching the 10 year unsheltered, storage requirement. Some ammo can manufacturers boast of a 29 year storage life when buried underground.

Plastic ammo cans are not capable of long-term sealing due to the inherent weaknesses in their design. They are fine for transporting ammo to the range and for short-term storage, but we would not recommend plastic ammo cans for long-term ammo storage. There are tests on YouTube where plastic ammo cans aren't even watertight in 3ft of water. Aside from the plastic ammo can options, most consumer grade metal ammo boxes are made with conventional rubber which dries out over time and cracks. The military has placed a lot of emphasis on upgrading the gasket material far beyond the capabilities of the conventional rubber found on Chinese produced metal ammo cans, plastic ammo cans, and most other consumer grade ammunition containers. We frequently get comments from customers that have had ammo ruined while stored in plastic ammo cans. The military spends a massive amount of money on metal ammo cans and has spent a lot of time trying to find a way to reduce the cost of ammunition packaging. So far, despite their best efforts, the military has not been able to find a suitable replacement for the metal ammo can which is a testament to their capability. The plastic cans don’t have the same quality of seal and the plastic itself isn’t as capable of maintaining the structural rigidity to preserve seal integrity. There are some mil-spec plastic ammo cans used in military applications but they are far more robust and are designed to be bolted closed to keep the seals intact. Plastic mil-spec ammo cans are used to reduce weight of the ammunition packaging for airborne transport rather than cost savings. The military grade plastic cans actually cost more than metal ammo cans.

 The ammo can is the major element that protects the ammo from the environment but inside the ammo can is where “the combat pack” items are found. The combat pack items are also the least understood features of the military ammo storage method and are what allow the ammunition to be put in action when needed. Military ammunition is packed in bandoliers, and loaded on stripper clips for quick loading into the magazine or on linked belts for use in machine guns. The combat pack components do not extend shelf life, but they are necessary to quickly implement ammunition loading and transport in the field and should be considered when storing ammunition if the intent is to be able to employ the ammunition in an emergency. All of the components required to perform a full military ammo repack are available in the store at CleanAmmoCans.com.

The US Military does not pack military ammo with desiccant but we feel this is an important departure from mil-spec, and is cheap insurance. Many of our customers have reported a discoloration of their ammo over time indicating moisture contamination inside of the ammo cans. If the ammunition containers are opened and closed, or initially packed in a humid environment, moisture can be introduced into the ammo cans. Dropping a single desiccant packet inside each ammo can before latching and sealing the ammo box is cheap insurance to keep your rounds fresh for the long haul. Desiccant packets absorb the moisture and humidity that is sealed inside the ammo can after it is closed. It is important to ensure your desiccant is fresh and has not reached its moisture capacity when you pack the ammo can or else you could actually introduce moisture into your cans. The ammo can desiccant sold by CleanAmmoCans.com is high quality, mil-spec, properly sized for ammo cans and is packed in a humidity-controlled room, inside aerospace quality, moisture barrier, foil packaging. Desiccant is an extra measure of protection since the proper sealing and latching of the ammo can will prevent moisture intrusion in most cases. However, its better to be safe than sorry when it comes to protecting your ammo. The CleanAmmoCans desiccant can be reset in the oven and reused.

Thinking about the location your ammo is stored is also important. Cool, stable temperatures are ideal for storing ammo. Avoid areas that have fluctuations in temperature that can cause the cans to sweat or condense. Garages get hot during the day and cool at night. It should also be noted that garages open up your ammo to theft easier than interior spaces or gun safes. Cool, dry, climate-controlled or temperature stable spaces are preferential when a subterranean ammo bunker is not in the budget. 

The current cost of ammunition is outrageous with no real end in sight. The next four years are going to be a stressful time for freedom loving Americans and will likely result in high ammo prices for the foreseeable future. Purchasing ammunition has become an investment. The days of buying 1000 rounds of 5.56mm for $300 and burning it down on Sunday-Gunday with family and friends are not in the cards for most of us anymore. Proper storage of ammo wasn’t that important previously when ammo was shot regularly at the range and replaced. Now that we are buying ammo to hold, and shoot much more sparingly, proper storage is really important. We hope this article has helped explain some of the inside knowledge about military ammunition storage and shed some light on what we believe to be the best long-term ammunition storage materials.