Does Ammunition Age?
Does ammunition age? Yes, ammunition can deteriorate over time, but age alone does not determine whether a cartridge remains usable. How ammunition is stored, including its exposure to heat, humidity, moisture, chemicals, and physical damage, can have a major effect on its condition.
A box of properly stored ammunition that is several years old is not automatically unsafe or unusable. On the other hand, ammunition that has spent years in high heat, high humidity, or poor storage conditions may deteriorate much faster.
There is also no single expiration date that applies to every type and brand of ammunition. Manufacturers may provide their own shelf-life recommendations. For example, Federal states that properly stored loaded ammunition and reloading components have a 10-year shelf life.
Does Ammunition Expire?
Ammunition does not have one universal expiration date.
The practical question is not simply how old the ammunition is, but how it was stored and what condition it is in now.
SAAMI recommends storing ammunition in a cool, dry location, away from heat sources, open flames, solvents, and other chemicals. It also warns that extended exposure to high temperatures can accelerate deterioration of the propellant.
That means two boxes of ammunition manufactured in the same year could have very different conditions years later if one was stored properly and the other was repeatedly exposed to heat and moisture.
How Long Does Ammunition Last?
The answer depends on the ammunition, manufacturer guidance, and storage conditions.
Properly stored ammunition can remain usable for many years. Federal currently gives a 10-year shelf-life recommendation for properly stored loaded ammunition and reloading components.
That should not be interpreted as meaning ammunition automatically becomes unusable on its tenth birthday.
Instead, manufacturer shelf-life guidance provides a useful reference point for properly stored products. Actual condition can be affected by environmental exposure and physical damage.
SAAMI defines powder deterioration as degradation of propellant that can be accelerated by improper storage conditions.
What Actually Makes Ammunition Deteriorate?
Several factors can affect ammunition over time:
- Excessive heat
- High humidity
- Water exposure
- Corrosion
- Chemical contamination
- Physical damage
- Poor storage conditions
- Long-term exposure to unfavorable environments
Age is therefore only one part of the equation.
For ammunition intended for long-term storage, controlling the environment is important. SAAMI recommends a cool, dry location and advises against leaving ammunition in vehicles or trunks for extended periods in direct sunlight or elevated temperatures.
How Does Heat Affect Old Ammunition?
Heat is one of the most important environmental factors affecting ammunition over time.
SAAMI states that prolonged exposure to high temperatures can accelerate deterioration of the propellant.
The concern is not simply that ammunition becomes “old” when exposed to heat. Elevated temperatures can accelerate chemical processes that would otherwise occur much more slowly.
SAAMI’s more recent guidance on fire and extreme-temperature exposure also explains that excessive heat can permanently degrade smokeless powder and primer ingredients without necessarily causing the cartridge to ignite.
That is why ammunition stored for years in a hot vehicle, attic, shed, or other high-temperature environment should not be treated the same as ammunition kept under appropriate storage conditions.
Does Humidity Affect Ammunition?
Yes. Moisture and humidity can contribute to ammunition deterioration.
SAAMI recommends storing ammunition in a cool, dry location. Exposure to unfavorable humidity conditions can contribute to corrosion and other forms of deterioration.
The cartridge case is particularly easy to inspect for external corrosion, but the absence of visible corrosion does not necessarily tell you everything about the condition of the internal components.
Keeping ammunition dry is therefore important for both long-term storage and reliable performance.
Can Ammunition Go Bad Without Looking Bad?
Yes.
Visible condition is useful, but it does not tell the entire story.
A cartridge can have an apparently normal exterior while its internal components have been affected by unfavorable storage conditions. SAAMI’s guidance on excessive heat specifically notes that energetic components can be degraded without necessarily producing obvious external evidence.
This is especially important when evaluating ammunition that has been exposed to extreme heat, fire, water, or other unusual conditions.
Does the Primer Deteriorate Over Time?
The primer can be affected by environmental conditions and physical damage.
For example, SAAMI notes that excessive heat can degrade primer ingredients and increase the likelihood of misfires.
Ammunition that has simply been stored properly for several years should not automatically be assumed to have a bad primer. However, ammunition that has experienced significant heat or other damaging conditions deserves additional caution.
Does Smokeless Powder Go Bad?
Smokeless powder can deteriorate.
SAAMI defines powder deterioration as degradation of propellant from decomposition of its explosive components and notes that improper storage conditions can accelerate that process.
Heat is particularly important because elevated temperatures can accelerate deterioration.
In its guidance on ammunition exposed to fire, SAAMI explains that excessive heat can cause the stabilizers used in modern smokeless powder to become depleted. Continued deterioration can eventually change the characteristics of the propellant.
This is one reason proper long-term storage matters more than simply tracking the manufacturing date.
Can Old Ammunition Become Less Reliable?
It can, particularly when ammunition has deteriorated because of unfavorable storage or exposure conditions.
Possible performance problems can include:
- Failure to fire
- Misfires
- Incomplete propellant combustion
- Reduced or inconsistent performance
- Other abnormal ammunition behavior
SAAMI notes that deterioration caused by temperature and humidity can result in lower pressures, incomplete burning, or failure to fire, while some forms of degradation can potentially produce increased pressure.
The important point is that old does not automatically mean unreliable, and new does not automatically mean undamaged.
Storage history matters.
Can You Shoot Old Ammunition?
Age by itself is not enough to determine whether ammunition should be used.
Before using older ammunition, consider:
- How old is it?
- How was it stored?
- Was it exposed to heat or humidity?
- Was it exposed to water or chemicals?
- Does the ammunition show corrosion or physical damage?
- Is the original packaging still available?
- Does the cartridge designation match the firearm?
SAAMI recommends inspecting ammunition before use and disposing of cartridges or shotshells that show physical damage such as corrosion, deep dents, or significant scratches. If there is doubt about the ammunition, SAAMI advises not to chamber or fire it.
How to Inspect Old Ammunition Before Use
Older ammunition should be examined for obvious signs of damage before it is considered for use.
Look for:
Corrosion
Check the cartridge case and other visible metal surfaces for corrosion or unusual discoloration.
Significant corrosion can weaken the case or interfere with proper chambering.
Dents and Deep Scratches
Deep dents, severe scratches, or other physical damage can compromise a cartridge.
SAAMI specifically identifies corrosion, deep dents, and scratches as examples of physical damage that should prompt disposal rather than use.
Damaged Bullets
Look for obvious deformation, unusual seating, or other visible damage to the projectile.
Damaged Packaging
Packaging can provide useful information about how ammunition was stored and handled. Original boxes also preserve product identification and other information that may be useful later.
Water or Chemical Exposure
Ammunition exposed to water, solvents, petroleum products, or other chemicals may have additional problems that are not immediately obvious.
SAAMI notes that chemicals can contaminate primer or powder mixtures and that external chemical exposure can contribute to case corrosion.
Does Old Ammo Have Lower Velocity?
Not necessarily.
Ammunition does not automatically lose a specific amount of velocity simply because it has reached a certain age.
Performance can be affected if the propellant has deteriorated, but the degree of change depends on the ammunition and the conditions under which it was stored.
For that reason, there is no reliable rule such as “ammunition loses X feet per second every year.”
Older ammunition that has been stored properly may perform normally, while ammunition exposed to excessive heat or other damaging conditions may experience abnormal performance.
Does Ammunition Get More Dangerous With Age?
Age itself does not mean ammunition becomes progressively more dangerous.
The more useful distinction is properly stored ammunition versus deteriorated or damaged ammunition.
Poor storage can cause deterioration that affects ignition and pressure. SAAMI notes that degraded propellant can potentially produce either lower or higher pressures depending on the condition of the powder.
This is why ammunition that has been exposed to extreme conditions should not be evaluated solely by its age or appearance.
What About Very Old Military or Surplus Ammunition?
Old military or surplus ammunition requires additional attention because its age, storage history, packaging, cartridge designation, and physical condition may vary.
The manufacturing date alone does not establish whether a particular cartridge is suitable for use.
If the ammunition’s identity or storage history is uncertain, do not guess. Original packaging, headstamp information, manufacturer documentation, and qualified professional guidance can help establish what the ammunition is and whether it is appropriate for a particular firearm.
Physical fit is not by itself proof of safe compatibility.
Does Rimfire Ammunition Age Differently?
Rimfire ammunition can also deteriorate with age and unfavorable storage.
As with centerfire ammunition, the relevant factors include environmental exposure, physical condition, and manufacturer guidance.
Do not assume that a particular type of ammunition is safe simply because it is old but appears clean, or unsafe solely because it is old. Evaluate the actual condition and storage history.
Does Reloaded Ammunition Have the Same Shelf Life?
Reloaded ammunition should not automatically be assigned the same shelf-life expectation as factory-loaded ammunition.
The components, loading process, storage history, and age of the individual components can all matter.
Factory ammunition comes with manufacturer specifications and packaging information. Reloaded ammunition may have a different history, particularly if the age and storage conditions of its components are unknown.
For ammunition with an uncertain loading or storage history, caution is appropriate.
How Should Ammunition Be Stored for Long-Term Storage?
For long-term storage, SAAMI recommends:
- A cool location
- A dry environment
- Protection from direct sunlight
- Separation from solvents and other chemicals
- Distance from heat sources and open flames
- Original packaging or suitable ammunition packaging
- Storage away from unauthorized access
SAAMI specifically warns against leaving ammunition in vehicles or trunks for extended periods when exposed to direct sunlight or elevated temperatures because this can accelerate propellant deterioration.
Good storage does not stop ammunition from aging, but it helps minimize the environmental factors that accelerate deterioration.
Should You Keep Old Ammunition in Its Original Box?
Keeping ammunition in its original packaging is useful for identification and storage.
The original packaging can preserve information about the cartridge, manufacturer, product, lot, and other details that may become important later.
SAAMI recommends storing ammunition in its original packaging or other packaging designed for that purpose.
This is particularly helpful when maintaining older ammunition because it reduces uncertainty about what the cartridges are and how they were originally packaged.
When Should Old Ammunition Not Be Used?
Age is not the only reason to set ammunition aside.
A cartridge should be treated as questionable if it shows obvious signs of physical damage or has been exposed to conditions known to compromise ammunition.
Examples include:
- Significant corrosion
- Deep dents
- Severe scratches
- Water or submersion exposure
- Fire or extreme heat exposure
- Chemical contamination
- Unknown or questionable cartridge identity
- Other obvious physical damage
SAAMI recommends not chambering or firing ammunition when there is doubt about its condition.
Old Ammunition vs. Properly Stored Ammunition
It helps to separate these concepts:
| Condition | What it tells you |
|---|---|
| Several years old, properly stored | Age alone does not establish deterioration |
| Several years old, unknown storage | Condition is harder to determine |
| Stored in high heat for extended periods | Greater concern for propellant deterioration |
| Stored in damp conditions | Greater risk of corrosion and moisture-related problems |
| Exposed to water | Requires separate assessment |
| Exposed to fire or extreme heat | May have hidden internal damage |
| Corroded or physically damaged | Should not be fired |
| Unknown cartridge identity | Should be identified before use |
The manufacturing date is useful information, but it is only one part of the assessment.
Does Ammunition Have a Shelf Life?
Yes, manufacturers can establish shelf-life guidance for their products.
Federal currently states that properly stored loaded ammunition and reloading components have a 10-year shelf life.
However, this should not be interpreted as a universal expiration date for every ammunition product.
Manufacturer guidance should take priority for a specific product, while storage conditions and physical condition remain important factors.
Frequently Asked Questions
Does ammunition expire?
There is no single expiration date that applies to all ammunition. Manufacturers may provide shelf-life guidance for their products. Federal currently states that properly stored loaded ammunition and reloading components have a 10-year shelf life.
How long does ammunition last?
Properly stored ammunition can remain usable for many years, but its condition depends on storage and environmental exposure. Heat, humidity, water, chemicals, and physical damage can accelerate deterioration.
Does ammo go bad with age?
It can deteriorate over time, but age alone does not determine its condition. Proper storage can help preserve ammunition, while poor storage can accelerate deterioration.
Is 10-year-old ammunition safe?
Ten years old does not automatically mean ammunition is unsafe. Federal’s current guidance gives a 10-year shelf life for properly stored loaded ammunition and reloading components, but the actual condition and manufacturer’s guidance should also be considered.
Can 20-year-old ammunition still work?
It can, depending on its condition and storage history. Age alone does not establish whether a particular cartridge will function properly.
Does heat make ammunition deteriorate faster?
Yes. SAAMI states that extended exposure to high temperatures can accelerate propellant deterioration.
Does humidity damage ammunition?
Humidity and moisture can contribute to corrosion and deterioration. SAAMI recommends storing ammunition in a cool, dry location.
Can old ammunition be dangerous?
Deteriorated or damaged ammunition can present safety risks. The concern is not simply its age, but what happened to the ammunition during storage and whether its components have deteriorated.
How should old ammunition be stored?
Keep it in a cool, dry location away from heat, sunlight, open flames, solvents, and other chemicals. Original packaging or packaging designed for ammunition is recommended.
The Bottom Line
Ammunition does age, but there is no universal rule that says it becomes unusable after a specific number of years. Storage conditions are a major part of the equation.
Properly stored ammunition can remain usable for many years. Federal currently gives a 10-year shelf-life recommendation for properly stored loaded ammunition and reloading components, while SAAMI emphasizes that heat, humidity, moisture, chemicals, and physical damage can affect ammunition condition.
For older ammunition, look beyond the date. Consider its storage history, inspect it for physical damage, verify its identity and compatibility, and follow the manufacturer’s guidance. If ammunition has been exposed to extreme heat, fire, water, or other damaging conditions, do not assume that age or appearance alone tells you whether it remains safe to use.