What Happens to Ammunition Exposed to Water?
What happens to ammunition exposed to water? It depends on the type of ammunition, how much water it encountered, and how long the exposure lasted. Limited exposure to rain or moisture is different from ammunition that has been completely submerged.
Water can cause corrosion, affect the cartridge case, and potentially reach the primer or propellant. Once moisture gets inside a cartridge, its effects may not be visible from the outside. SAAMI’s current guidance specifically distinguishes ordinary light moisture exposure from ammunition that has been submerged and warns that water exposure can compromise ammunition performance depending on the circumstances.
The important rule is simple: do not assume that wet ammunition is safe to fire simply because it looks normal after drying.
Quick Answer: What Does Water Do to Ammunition?
Water exposure can affect ammunition in several ways:
- Corrosion can develop on the cartridge case.
- Moisture can potentially reach the primer or propellant.
- Cartridge cases can deteriorate under sufficiently severe exposure.
- Priming compounds or propellant can become contaminated.
- Ammunition may fail to fire, burn incompletely, or otherwise perform unpredictably.
- Rimfire ammunition is particularly susceptible to moisture exposure.
- Submerged ammunition presents a different situation from brief exposure to rain or damp conditions.
SAAMI states that water, solvents, petroleum products, acids, ammonia, and similar substances can damage ammunition. If moisture enters the cartridge, it can affect the primer or propellant and potentially result in a failure to fire, incomplete burning, or delayed firing.
What Happens When Ammo Gets Wet?
The answer depends largely on how the ammunition became wet.
A few drops of rain on properly packaged centerfire ammunition are not equivalent to cartridges that spent hours or days underwater.
SAAMI’s 2025 guidance separates ammunition exposed to normal rain or moisture from ammunition that has been completely submerged. Centerfire rifle, handgun, and shotshell ammunition can tolerate limited exposure to light rain or moisture when the exposure is limited and the cartridges are promptly wiped dry.
That does not mean all wet ammunition can safely be reused. The nature and degree of the exposure matter.
What Happens to Ammunition That Is Submerged?
Submersion is substantially more serious than brief exposure to rain.
When ammunition is submerged, several variables can affect the outcome, including:
- Cartridge type
- Depth of the water
- Length of time submerged
- Water temperature
- Condition of the ammunition before exposure
- Type of water
- Whether contaminants were present
- Condition of the cartridge and its sealing
SAAMI’s 2025 guidance explains that the effects of submersion cannot always be determined simply by looking at an individual cartridge.
For this reason, previously submerged ammunition should not simply be dried and treated as normal ammunition.
Can Water Get Inside a Cartridge?
It can.
A loaded cartridge is designed to protect its internal components, but water exposure can compromise that protection under sufficiently severe conditions.
If moisture reaches the primer or propellant, it can affect their performance. SAAMI notes that moisture or chemicals entering a cartridge can cause failures to fire, incomplete burning, or delayed firing.
This is one reason visual inspection alone cannot establish that previously submerged ammunition is safe.
A cartridge may appear normal externally while having experienced internal exposure.
What Happens to the Primer?
The primer is one of the components that can be affected by moisture.
If water or another contaminant reaches the primer composition, the cartridge may fail to ignite properly.
Potential outcomes can include:
- Failure to fire
- Delayed ignition
- Inconsistent ignition
SAAMI specifically identifies moisture entering the cartridge as a potential cause of failure to fire or delayed firing.
A cartridge with suspected water damage should therefore not be tested by firing it.
What Happens to the Propellant?
Moisture can also affect the propellant inside a cartridge.
Depending on the degree of exposure and the condition of the ammunition, contamination can affect how the propellant burns.
SAAMI notes that environmental or chemical exposure can result in incomplete burning or other changes in ammunition performance.
The important point is that water damage is not necessarily limited to visible rust or discoloration.
Internal contamination may not be apparent from the outside.
Can Water Cause Ammunition to Rust?
Yes.
Water exposure can promote corrosion of metallic cartridge components.
External corrosion can potentially:
- Weaken the cartridge case
- Affect chambering
- Alter the physical condition of the cartridge
- Indicate that the ammunition has experienced prolonged moisture exposure
SAAMI recommends inspecting ammunition before use and not using ammunition showing signs of physical damage such as corrosion, deep dents, or significant scratches.
The presence of corrosion should therefore not be dismissed as merely cosmetic.
Is Rain-Damp Ammo the Same as Submerged Ammo?
No.
This is one of the most important distinctions when discussing water exposure.
SAAMI’s 2025 guidance says centerfire rifle, handgun, and shotshell ammunition is reasonably tolerant of limited exposure to light rain, snow, or damp ground when the exposure is limited and the cartridges are wiped dry immediately.
Submerged ammunition is a different situation.
The longer and more complete the water exposure, the greater the uncertainty about what happened inside the cartridge.
Is Rimfire Ammo More Sensitive to Water?
Yes.
SAAMI specifically states that rimfire ammunition is more susceptible to moisture damage than other ammunition types because of its unique cartridge construction. SAAMI recommends making every effort to prevent rimfire ammunition from exposure to rain, snow, or water-soaked ground.
That makes the distinction between cartridge types particularly important when evaluating water exposure.
What About Shotshells?
Shotshells can also be affected by water exposure.
Their construction differs from metallic centerfire cartridges, and the condition of the hull, primer, propellant, and other components can matter.
As with other ammunition, brief incidental moisture exposure should not automatically be equated with complete submersion.
If a shotshell has been significantly exposed to water or shows visible damage, do not assume that drying it makes it suitable for use.
Can You Dry Wet Ammunition?
For lightly exposed ammunition, SAAMI’s guidance distinguishes limited rain or moisture exposure from submersion and notes that cartridges exposed to light moisture should be wiped dry promptly.
However, submerged ammunition should not be treated as ordinary wet ammunition that simply needs to dry out.
SAAMI’s 2025 guidance specifically warns against attempting to salvage previously submerged ammunition and against using direct heat to dry it. Direct heat can affect the propellant and potentially change its burning characteristics.
Do not use an oven, heater, flame, or other direct heat source to dry ammunition.
Should You Fire Water-Exposed Ammunition to See If It Works?
No.
Firing a questionable cartridge is not a reliable way to determine whether water exposure damaged it.
The cartridge could have internal damage or contamination that cannot be identified through a simple visual inspection.
SAAMI’s guidance states that ammunition exposed to water can have effects that are not necessarily predictable for each individual cartridge.
If ammunition has been significantly exposed to water, follow the manufacturer’s or appropriate local authority’s guidance instead of using it as a test.
What If the Ammo Was Completely Submerged?
Treat complete submersion differently from a brief encounter with rain.
SAAMI’s specific 2025 guidance for submerged ammunition recommends not attempting to salvage or use ammunition that has been submerged. It also advises consumers to contact local law enforcement for disposal instructions and says previously submerged ammunition should not be shipped back to the manufacturer.
If ammunition has been recovered from floodwater or another body of water:
- Do not fire it.
- Do not attempt to dry it with direct heat.
- Keep it separate from ammunition intended for use.
- Preserve the original packaging and identifying information if available.
- Follow applicable local disposal requirements.
- Seek guidance from the appropriate local authority.
What If the Ammo Was Exposed to Floodwater?
Floodwater presents additional uncertainty because it may contain dirt, silt, chemicals, salt, sewage, or other contaminants.
The condition of the ammunition before the flooding and the nature and duration of the exposure also matter.
SAAMI’s 2025 guidance specifically addresses ammunition exposed to water and water-based firefighting agents because the degree of exposure can affect ammunition performance.
Flood-exposed ammunition should not be treated like cartridges that simply got caught in a rain shower.
What If the Ammo Only Got Wet for a Few Minutes?
Brief exposure is not automatically equivalent to permanent damage.
SAAMI states that centerfire rifle, handgun, and shotshell ammunition is reasonably tolerant of limited exposure to light rain, snow, or damp ground when the exposure is limited and the cartridges are wiped dry immediately.
However, this guidance should not be stretched to cover ammunition that was submerged, repeatedly exposed to moisture, visibly corroded, or otherwise damaged.
The condition of the individual cartridge still matters.
What Signs of Water Damage Should You Look For?
Inspect ammunition for obvious signs of moisture exposure, including:
- Rust or corrosion
- Water staining
- Damaged packaging
- Discoloration
- Deteriorated cases or hulls
- Damaged primers
- Deformed cartridges
- Other unusual physical changes
Remember that a lack of visible damage does not prove that submerged ammunition is unaffected.
SAAMI specifically warns that hidden damage can occur following water exposure.
What Should You Do With Water-Damaged Ammunition?
If ammunition has been significantly exposed to water or has been submerged, do not put it back into your normal ammunition supply.
Keep it separate and follow appropriate disposal guidance.
SAAMI states that ammunition should be disposed of in accordance with applicable federal, state, and local regulations. For previously submerged ammunition, its 2025 guidance directs consumers to contact local law enforcement for disposal instructions.
Do not assume that ordinary household trash, recycling, or an ordinary ammunition return shipment is an appropriate disposal method.
What Information Should You Keep?
If water exposure has affected commercially packaged ammunition, keep the original packaging when practical.
Useful information includes:
- Manufacturer
- Cartridge designation
- Product name
- Product number or symbol
- Lot number
- Quantity
- Type of water exposure
- Approximate duration of exposure
- Visible condition of the packaging
The lot number can help identify the particular production batch if you need to contact the manufacturer.
What About Ammo That Was Stored in a Damp Area?
Ammunition does not need to be completely submerged before moisture becomes a concern.
SAAMI notes that extended exposure to high humidity can damage ammunition. Water and other environmental or chemical exposures can also affect ammunition performance.
Ammunition should therefore be stored in a cool, dry location and protected from water, excessive humidity, solvents, chemicals, and other damaging conditions.
If ammunition has been stored in a damp environment for an extended period, inspect it carefully before considering it for use.
Water Exposure vs. Ammunition Condition
It is useful to separate two questions:
How was the ammunition exposed to water?
and
What condition is the ammunition in now?
A cartridge that briefly encountered rain is not the same as ammunition recovered after prolonged submersion.
Likewise, visible corrosion, damaged packaging, or other physical changes can provide additional evidence about the severity of exposure.
Do not reduce the entire assessment to whether the cartridge “looks dry.”
What About Water-Damaged Ammunition Packaging?
The packaging itself can provide important clues.
Look for:
- Water stains
- Discoloration
- Swelling
- Torn cardboard
- Damaged labels
- Deteriorated trays
- Evidence that water reached the ammunition
Keep the packaging whenever possible, especially if the ammunition may need to be identified or reported to the manufacturer.
Can You Save Water-Exposed Ammunition by Cleaning It?
Do not attempt to restore significantly water-exposed ammunition by polishing, sanding, applying chemicals, or otherwise modifying the cartridges.
Cleaning the outside does not establish the condition of the primer or propellant inside.
If the ammunition has been submerged or significantly compromised, follow the applicable disposal guidance rather than attempting to restore it.
Frequently Asked Questions
What happens to ammunition exposed to water?
Water can cause corrosion and, if it reaches the cartridge interior, can affect the primer or propellant. The severity depends on the type and duration of exposure.
Can wet ammo still be fired?
Do not assume that wet ammunition is safe to fire. Limited rain exposure is different from significant water exposure or submersion. Ammunition that has been submerged should not be salvaged or used according to SAAMI’s 2025 guidance.
Is ammunition ruined if it gets rained on?
Not necessarily. SAAMI says centerfire rifle, handgun, and shotshell ammunition can tolerate limited exposure to light rain or moisture when the exposure is limited and the cartridges are wiped dry immediately. Rimfire ammunition is more susceptible to moisture damage.
What happens if ammunition is submerged?
Submersion can compromise ammunition depending on the cartridge type and the nature and duration of the exposure. SAAMI advises against attempting to salvage or use previously submerged ammunition.
Can I use a hair dryer or heater to dry wet ammo?
Do not use direct heat to dry ammunition. SAAMI specifically warns that direct heat can degrade propellant and potentially alter its burning characteristics.
Is rimfire ammunition more sensitive to water?
Yes. SAAMI states that rimfire ammunition is more susceptible to moisture damage than other ammunition types because of its construction.
Can water damage ammunition without visible rust?
Yes. Moisture can potentially reach internal components without producing obvious external corrosion. SAAMI notes that hidden damage can occur following water exposure.
What should I do with ammunition recovered from floodwater?
Do not fire or attempt to salvage it. Keep it separate and follow appropriate disposal guidance. SAAMI’s 2025 guidance directs consumers to contact local law enforcement for disposal instructions for previously submerged ammunition.
Final Takeaway
Water exposure does not affect every cartridge in exactly the same way. Brief exposure to rain or moisture is different from prolonged exposure or complete submersion.
Centerfire rifle, handgun, and shotshell ammunition can tolerate limited light moisture exposure when handled appropriately, while rimfire ammunition is more susceptible to moisture damage. Significant water exposure can affect the cartridge case and potentially the primer or propellant, including damage that may not be visible externally.
For ammunition that has been submerged, the safest approach is not to experiment with drying, cleaning, or firing it. Follow SAAMI’s current guidance and applicable local disposal requirements.
When it comes to water-exposed ammunition, the amount and type of exposure matter—but uncertainty is a reason to stop, not a reason to test the cartridge in a firearm.