⚡ Quick Answer:
Yes, ammunition can go bad. Modern ammunition stored properly can last 10-50+ years, but exposure to moisture, extreme temperatures, and improper storage can cause dangerous deterioration in as little as 12 months. Bad ammo can cause misfires, hangfires, squib loads, or even catastrophic firearm damage.
If you've ever opened an old ammo box and wondered "Is this still safe to shoot?" you're not alone. Every year, shooters waste thousands of dollars on deteriorated ammunition—or worse, risk injury from firing compromised rounds. This guide will teach you exactly how to identify bad ammunition, understand what causes deterioration, and most importantly, how to prevent it.
The 7 Warning Signs Your Ammo Has Gone Bad
Before we dive into the science, here are the immediate red flags that indicate ammunition should NOT be fired:
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Green/White Corrosion
Verdigris (green) or white powdery corrosion on brass indicates chemical breakdown. Never fire these rounds.
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Bulging or Deformed Cases
Swollen cases indicate internal pressure changes or moisture damage. Can cause chamber explosions.
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Loose Bullets
Bullets that spin or push into the case easily indicate neck tension loss. Risk of squib loads.
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Heavy Tarnishing
Dark brown/black tarnish may be cosmetic but indicates age and potential internal degradation.
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Damaged Primer
Pushed-in, cracked, or missing primers will cause misfires. Check each round before loading.
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Powder Leaking
Any powder residue outside the case indicates compromised seal. Do not use.
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Light Patina
Slight discoloration or dull finish is usually cosmetic only. Safe to fire if no other issues present.
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NEVER Fire Ammunition If You're Unsure
When in doubt, throw it out. No amount of money saved is worth a destroyed firearm or injury. Compromised ammunition can cause:
- Squib loads (bullet stuck in barrel)
- Hangfires (delayed ignition)
- Case head separation
- Catastrophic firearm failure
How Long Does Ammunition Really Last?
The shelf life of ammunition depends on three critical factors: the type of ammunition, storage conditions, and the quality of manufacturing. Here's what you can expect under different conditions:
| Storage Conditions |
Expected Shelf Life |
Common Issues |
Ideal
(50-70°F, <50% humidity, sealed container) |
50+ years |
Minor cosmetic tarnishing only |
Good
(Climate controlled, original packaging) |
20-30 years |
Some tarnishing, occasional duds |
Average
(House storage, variable temperature) |
10-15 years |
Tarnishing, 1-2% failure rate |
Poor
(Garage, basement, high humidity) |
3-5 years |
Corrosion, high misfire rate |
Bad
(Extreme temps, moisture exposure) |
6-12 months |
Dangerous deterioration |
Shelf Life by Ammunition Type
| Ammunition Type |
Typical Shelf Life |
Notes |
Modern Centerfire
(9mm, .223, .308, etc.) |
10-50+ years |
Most stable; sealed primers resist moisture |
Rimfire
(.22LR, .17HMR) |
5-10 years |
More sensitive to moisture; primer compound degrades faster |
| Shotshells |
5-10 years |
Paper hulls: 2-5 years; Plastic hulls: 10+ years |
| Military Surplus |
30-75+ years |
Often sealed; made for long-term storage |
| Reloaded/Handloads |
2-10 years |
Depends on components and quality of reloading |
What Actually Causes Ammunition to Go Bad?
Understanding the enemies of ammunition helps you prevent deterioration:
1. Moisture (The #1 Killer)
Humidity above 60% starts chemical reactions that:
- Corrode brass cases (verdigris formation)
- Degrade primer compounds (causing misfires)
- Clump gunpowder (affecting burn rate)
- Rust steel cases and bullets
2. Temperature Extremes
Both hot and cold extremes cause problems:
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Heat (>120°F): Breaks down powder and primer compounds
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Cold (<32°F): Creates condensation when temperature changes
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Fluctuation: Repeated expansion/contraction loosens bullets
3. Oil and Solvents
Petroleum products can:
- Penetrate case necks and deactivate powder
- Contaminate primers (causing failures)
- Break down case sealants
4. Physical Damage
Rough handling causes:
Dented cases (chambering issues)
Pushed-back bullets (pressure spikes)
Damaged primers (misfires)
Visual Guide: Good vs. Bad Ammunition
🔍 Brass Case Condition Guide
✅ SAFE - Shiny Brass
New or well-preserved
✅ SAFE - Dull/Patina
Normal aging, cosmetic only
⚠️ CAUTION - Dark Tarnish
Test fire a few rounds first
🚫 DANGER - Green Corrosion
Do not use - dispose properly
🎯 Primer Condition Guide
✅ SAFE - Flush & Intact
Proper primer seating
⚠️ CAUTION - Slightly Recessed
May cause light strikes
🚫 DANGER - Pushed In/Out
Will not fire properly
🚫 DANGER - Corroded
Unreliable ignition
How to Test Questionable Ammunition
If you have ammunition that looks marginal but not obviously dangerous, here's how to safely test it:
-
Visual Inspection: Check every round individually under good light
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Shake Test: Listen for loose powder (indicates breakdown)
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Bullet Wiggle Test: Check if bullets move in the case
-
Chamber Check: Ensure rounds chamber smoothly
-
Test Fire Protocol:
- Start with 1 round
- Listen for unusual report
- Check for proper ejection
- Inspect fired case for splits or signs of overpressure
- If good, test 5 more rounds before trusting the batch
The Do's and Don'ts of Ammunition Storage
✅
DO's for Long-Term Storage
✓
Store in airtight, waterproof containers
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Maintain 30-50% humidity levels
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Keep temperature between 55-85°F
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Use desiccants in storage containers
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Label with purchase/storage dates
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Rotate stock (first in, first out)
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Store in original packaging when possible
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Inspect stored ammo annually
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DON'Ts That Ruin Ammo
✗
Store in basements or attics
✗
Leave in vehicles long-term
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Use WD-40 or oil near ammo
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Mix different calibers together
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Store near chemicals or solvents
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Bury underground (moisture trap)
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Ignore signs of deterioration
Special Cases: When Good Ammo Goes Bad Fast
Steel Case Ammunition
Steel case ammo (Wolf, Tula, etc.) deteriorates faster than brass:
- Polymer coatings can trap moisture
- Rust develops quickly in humidity
- Typical shelf life: 5-7 years vs. 20+ for brass
Surplus Military Ammunition
Can be excellent or terrible depending on storage:
- Sealed spam cans: Often good for 50+ years
- Loose surplus: Check for corrosive primers
- Always clean firearms immediately after firing
Reloaded Ammunition
Variables in quality mean shorter shelf life:
- Unknown powder/primer combinations
- Potential contamination during loading
- Recommend using within 2-3 years
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Pro Tip: The Nickel Test
Military armorers use this quick test: Drop a round from 6 inches onto a hard surface. Good ammo makes a clear "ring." Bad ammo sounds dull or "thud-like" due to powder breakdown or moisture. Not 100% reliable but a useful quick check.
Frequently Asked Questions
Q: Can old ammo damage my gun?
Yes. Deteriorated ammunition can cause squib loads (bullet stuck in barrel), case head separation, or overpressure situations that can destroy your firearm and cause injury. Never fire ammunition you're unsure about.
Q: Is 30-year-old ammo safe to shoot?
It depends entirely on storage conditions. Properly stored ammunition can last 50+ years. Check for the warning signs listed above. If it looks good and passes visual inspection, test fire a few rounds carefully before trusting the batch.
Q: Why did my ammo turn green?
Green corrosion (verdigris) forms when brass is exposed to moisture and ammonia compounds. This indicates chemical breakdown of the case material. Do not fire green corroded ammunition as it may have weakened case walls.
Q: Can I clean corroded ammo?
Light tarnish can be cleaned with a dry cloth, but true corrosion (green/white buildup) indicates chemical changes that cleaning won't fix. The internal components may be compromised even if you clean the exterior. It's not worth the risk.
Q: How should I dispose of bad ammunition?
Never throw ammunition in regular trash. Options include: (1) Contact local police for disposal programs, (2) Take to hazardous waste collection events, (3) Some ranges accept bad ammo for disposal, (4) Pull bullets and dispose of components separately (advanced reloaders only).
Q: Does ammo expire like food?
No, ammunition doesn't have a true expiration date. Unlike food, it doesn't spoil on a predictable timeline. Deterioration depends entirely on storage conditions. Ammo stored in perfect conditions can outlast ammo that's 40 years newer but poorly stored.
Q: What humidity level ruins ammunition?
Humidity above 60% accelerates deterioration. Above 70%, corrosion can begin within months. Ideal storage humidity is 30-50%. Use desiccants or dehumidifiers in storage areas to maintain proper levels.
The Bottom Line: Prevention Is Everything
Bad ammunition isn't just about wasted money—it's a serious safety hazard. The good news? With proper storage, modern ammunition can last decades. The key is controlling moisture, temperature, and physical protection.
Remember these critical points:
- Moisture is ammunition's worst enemy
- Green corrosion means do not use
- When in doubt, throw it out
- Proper storage extends life from years to decades
- A quality storage container pays for itself
Whether you're storing a few boxes for home defense or thousands of rounds for competition, investing in proper storage isn't optional—it's essential for safety and economy.
Safety Notice: This guide provides general information about ammunition deterioration. Always consult your firearm's manual and follow manufacturer guidelines. When in doubt about ammunition safety, dispose of it properly. Never fire ammunition that shows signs of deterioration.
About This Guide: Created by Evergreen Cases based on industry standards, military specifications, and decades of shooter experience. For more information about proper ammunition storage solutions, visit our complete ammo case collection.
