How to Store Bulk 5.56: Cans, Humidity, and Rotation
How to store 5.56 ammo becomes increasingly important as your supply grows. A few boxes sitting in a dry closet are relatively simple to manage, but storing several hundred or several thousand rounds requires more attention to moisture, temperature, organization, and inspection.
Proper storage does not require an elaborate setup. The basic goal is to keep ammunition in a cool, dry, stable environment, protect it from unnecessary moisture and contaminants, and organize your supply so older ammunition does not get forgotten.
SAAMI recommends storing ammunition in its original packaging or other packaging designed for that purpose and keeping it in a cool, dry location away from solvents, chemicals, heat sources, and open flames.
How Should You Store 5.56 Ammo?
The simplest approach is to keep factory ammunition in its original packaging and place it somewhere that is cool, dry, secure, and protected from major temperature swings.
For larger quantities, a purpose-designed ammunition container can make organization and moisture management easier. The container itself, however, is only part of the storage system. Where you put that container matters too.
A good storage location should:
- Stay relatively cool and dry
- Avoid direct sunlight
- Avoid major temperature fluctuations
- Be away from water and areas prone to condensation
- Be away from solvents, petroleum products, and other chemicals
- Keep ammunition inaccessible to unauthorized people
- Allow you to inspect and organize your stock periodically
SAAMI also advises against leaving ammunition in vehicles for extended periods, particularly when exposed to direct sunlight or elevated temperatures.
Why Humidity Matters for 5.56 Ammo
Humidity is one of the main environmental concerns when storing ammunition for extended periods.
Ammunition is manufactured to withstand normal environmental conditions, but unnecessary exposure to moisture can contribute to corrosion and deterioration. The goal of long-term storage is therefore not simply to keep the ammunition away from visible water. It is to avoid creating an environment where moisture can accumulate around the cartridges over time.
This is particularly important in basements, garages, sheds, and other locations where humidity can fluctuate substantially.
A dry indoor storage area is generally easier to manage than an outdoor or semi-exposed location.
What About Condensation?
Temperature changes can also matter because a container that repeatedly moves between warm and cold conditions can experience condensation.
This is one reason a stable storage environment is preferable to repeatedly moving ammunition between very different temperatures.
The objective is straightforward: avoid unnecessary moisture exposure and keep the storage environment stable.
Are Ammo Cans Good for 5.56 Storage?
Ammunition cans can be useful for organizing bulk 5.56, particularly when you are storing multiple boxes or large quantities.
A suitable container can provide physical protection and make it easier to separate different loads, lot numbers, or purchase dates.
But an ammo can is not automatically a moisture-proof solution simply because it has a lid.
Before using any storage container, consider:
- Whether it is designed for ammunition or similar storage purposes
- The condition of its seal and closure
- Whether the container is clean and dry
- Whether it will be stored in an appropriate environment
- Whether the ammunition remains identifiable and organized
SAAMI recommends original packaging or packaging specifically designed for ammunition storage.
For factory ammunition, there is also value in keeping the original boxes. They provide useful information such as cartridge designation, bullet weight, manufacturer, product identification, and lot information.
Should You Keep 5.56 Ammo in the Original Boxes?
For many shooters, keeping factory 5.56 ammunition in its original packaging is the simplest approach.
The boxes make it easier to identify exactly what you have without opening every container. They can also help you keep different loads separated.
For example, you may have:
- 55-grain FMJ
- 62-grain FMJ
- 77-grain match ammunition
- Different manufacturers
- Different bullet constructions
- Different lots of the same ammunition
Keeping these separated makes inventory management easier and reduces the chance of accidentally mixing different loads.
SAAMI specifically recommends storing ammunition in its original packaging or other packaging designed for that purpose.
Should You Use Desiccant With Stored 5.56?
A desiccant can be useful as part of a moisture-control strategy, particularly when ammunition is kept in a closed container.
The important point is that desiccant is not a substitute for proper storage conditions.
A desiccant packet does not make a damp basement an ideal ammunition-storage environment. Likewise, it does not eliminate the need to inspect the ammunition or maintain the storage container.
Think of moisture control as a system:
Good location + appropriate container + controlled moisture + periodic inspection
That approach is more reliable than depending on one product or storage trick.
Where Should You Not Store Bulk 5.56?
Some locations are simply poor choices for long-term ammunition storage.
Avoid Excessive Heat
Ammunition should not be stored around heat sources or exposed to unnecessarily high temperatures.
SAAMI recommends a cool, dry storage location and specifically warns against extended storage in vehicles exposed to direct sunlight or elevated temperatures.
An enclosed vehicle can become extremely hot in direct sunlight, making it a poor long-term storage location.
Avoid Damp Areas
A location that regularly experiences high humidity, leaks, flooding, or condensation is not ideal for bulk ammunition.
This includes areas immediately adjacent to plumbing, locations subject to water intrusion, and floors where containers may be exposed to moisture.
Avoid Chemicals and Solvents
Ammunition should also be kept away from solvents, petroleum products, and other chemicals.
SAAMI specifically includes solvents and other chemicals among materials ammunition should be stored away from.
Avoid Uncontrolled Access
Bulk ammunition should be stored securely and separately from firearms, with access limited to authorized people. SAAMI recommends that ammunition be stored separately from firearms and made inaccessible to unauthorized persons.
Always follow applicable federal, state, and local storage requirements.
How Long Does 5.56 Ammo Last?
There is no single expiration date that applies to every box of 5.56.
Storage conditions make a major difference.
SAAMI notes that ammunition stored in factory packaging under ordinary variations in temperature and humidity can be expected to perform safely and satisfactorily when properly stored, while extreme temperatures should be avoided.
Federal states that loaded ammunition has a 10-year shelf life when stored properly in a cool, dry location protected from direct sunlight.
That should not be interpreted as meaning ammunition becomes unusable automatically after 10 years. Rather, manufacturers’ guidance and the actual condition of the ammunition should be considered.
For older ammunition, condition matters more than simply looking at the calendar.
How to Rotate Bulk 5.56 Ammo
Rotation is useful when maintaining a large ammunition inventory.
The basic principle is first in, first out: use older stock before newer stock when practical.
For example, if you already have 500 rounds stored and later add another 1,000 rounds, organize the supply so you know which ammunition was stored first.
You can track:
- Purchase date
- Manufacturer
- Product
- Bullet weight
- Lot number
- Quantity
- Storage location
You do not need an elaborate inventory system. A simple label or spreadsheet can be enough.
Why Rotation Helps
Rotation prevents older ammunition from being forgotten at the back of a storage area.
It also gives you a reason to periodically inspect your inventory rather than leaving everything untouched for years.
SAAMI recommends inspecting ammunition before use and disposing of cartridges showing physical damage such as corrosion, deep dents, or significant scratches.
Inspect 5.56 Before Shooting
Storage is only part of ammunition maintenance.
Before using older or previously stored ammunition, look for obvious signs of damage or deterioration.
Pay attention to:
- Corrosion
- Damaged cases
- Deep dents
- Significant scratches
- Damaged primers
- Projectile movement or other unusual appearance
- Evidence of water exposure
If a cartridge appears damaged or questionable, do not assume it is safe simply because it is ammunition from a reputable manufacturer.
SAAMI advises that ammunition showing physical damage should not be fired and recommends obtaining appropriate disposal guidance when necessary.
What If 5.56 Ammo Gets Wet?
Brief exposure to light rain or moisture does not necessarily mean centerfire rifle ammunition is ruined, but ammunition that has been exposed to water should be handled carefully.
SAAMI’s 2025 guidance distinguishes between limited exposure to rain or damp conditions and ammunition that has been completely submerged. For limited exposure, SAAMI says centerfire rifle ammunition is reasonably tolerant if exposure is limited and the cartridges are wiped dry immediately. Ammunition should not be stored in a manner that traps water around the cartridges.
Submerged ammunition is a different situation. The depth and duration of exposure, cartridge type, and other factors can affect what should be done.
If ammunition has been submerged, follow manufacturer or SAAMI guidance rather than assuming it can simply be dried and used.
A Practical Bulk 5.56 Storage System
For shooters maintaining a larger supply, a simple organization system can work well.
1. Keep Factory Packaging
Whenever practical, leave ammunition in its original boxes.
2. Group Similar Loads
Keep different bullet weights, constructions, manufacturers, and lots organized separately.
3. Use Appropriate Containers
Place packaged ammunition in suitable storage containers when additional physical organization or protection is useful.
4. Label the Containers
Mark the outside with enough information to identify what is inside without repeatedly opening the container.
5. Record Older Stock
Keep track of which ammunition entered storage first.
6. Store in a Stable Environment
Choose a cool, dry location away from direct sunlight, chemicals, heat sources, and water.
7. Inspect Before Use
Periodically check older ammunition and inspect individual cartridges before shooting.
This system is simple enough for a few hundred rounds but can also scale to a much larger inventory.
Common 5.56 Storage Mistakes
Leaving Ammo in a Vehicle
A vehicle may be convenient for transportation, but it is not an appropriate long-term storage environment because temperatures can become very high.
Storing Ammo Directly on a Damp Floor
Ammunition stored in an area vulnerable to moisture should have appropriate protection from the environment. SAAMI’s broader storage guidance also recommends keeping ammunition away from moisture-prone conditions.
Mixing Everything Together
Mixing different loads and lots into one container makes identification and rotation harder.
Ignoring Old Ammunition
Bulk storage makes it easy to forget about older boxes. A basic rotation system helps prevent this.
Treating an Ammo Can as a Complete Storage Solution
A container cannot compensate for a poor storage environment. The location, temperature, humidity, packaging, and condition of the ammunition all matter.
5.56 Ammo Storage Checklist
Before putting bulk 5.56 into long-term storage, check the following:
| Storage factor | What to look for |
|---|---|
| Location | Cool, dry, stable environment |
| Packaging | Original or purpose-designed packaging |
| Moisture | Protected from water and excessive humidity |
| Temperature | Avoid excessive heat and direct sunlight |
| Chemicals | Keep away from solvents and petroleum products |
| Organization | Separate different loads and lots |
| Rotation | Use older stock before newer stock |
| Inspection | Check for corrosion or physical damage |
| Security | Restrict access to authorized people |
| Vehicle storage | Avoid long-term storage in vehicles |
FAQ
Does 5.56 ammo need to be stored in an ammo can?
No. An ammo can is not inherently required for storing 5.56. Factory packaging in a suitable cool, dry environment can be appropriate. Purpose-designed containers can make bulk storage easier to organize and protect.
Does humidity ruin 5.56 ammo?
Excessive moisture exposure can contribute to ammunition deterioration and corrosion. Keeping 5.56 in a cool, dry environment and preventing water from being trapped around the cartridges helps reduce that risk.
Should 5.56 ammo be stored in its original box?
Keeping ammunition in its original packaging is a practical way to preserve identification and organization, and SAAMI recommends original packaging or packaging designed for ammunition storage.
Can you store 5.56 ammo in a garage?
It depends on the conditions. A garage that experiences substantial heat, humidity, condensation, or temperature swings is less suitable than a stable indoor storage area.
How should you rotate bulk 5.56 ammo?
A simple first-in, first-out system works well. Label older and newer stock clearly and use older ammunition before newer ammunition when practical.
How long can properly stored 5.56 ammo last?
Properly stored ammunition can have a long service life, but there is no universal expiration date for every cartridge. Federal states that properly stored loaded ammunition has a 10-year shelf life, while SAAMI emphasizes proper storage conditions and ammunition condition.
Final Takeaway
Storing bulk 5.56 does not have to be complicated. The fundamentals are straightforward: keep it cool, dry, organized, protected from chemicals and excessive heat, and inaccessible to unauthorized people.
Use appropriate packaging or containers, keep track of older stock, and inspect ammunition before use. An ammo can can be a useful part of the system, but the storage environment itself is just as important.
For long-term storage, the goal is not to create a perfect environment. It is to avoid the conditions that unnecessarily accelerate ammunition deterioration and to maintain an inventory you can identify and inspect years later.