How To Tell If Ammo Is Bad: The Complete Technical Inspection Guide

Determining whether ammunition is compromised requires a systematic visual, tactile, and olfactory inspection of the casing, primer, and projectile. By evaluating corrosion, physical deformation, and chemical breakdown against military and SAAMI specifications, shooters can reliably identify degraded cartridges before they cause dangerous malfunctions like squib loads or out-of-battery detonations.

Pre-Inspection Setup and Environmental Standards

Assessing large stockpiles of surplus, factory-new, or handloaded ammunition requires a controlled environment and basic diagnostic tools. Before opening surplus battle packs or commercial ammunition cans, establish a clean, well-lit workbench free of open flames, static-generating materials, and moisture.

• Essential tools and gear include a digital caliper with a precision of 0.0005 inches, an impact kinetic bullet puller, a lint-free microfiber cloth, and a dedicated high-intensity LED inspection light.
• Required foundational knowledge encompasses an understanding of SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) dimensional tolerances, standard cartridge case wall thicknesses, and the distinct smell of degrading propellant.
• Budget and duration expectations average under twenty dollars for a basic caliper and puller set, while inspecting a standard 1,000-round lot takes approximately forty-five to sixty minutes of methodical sorting.

Step-by-Step Ammunition Evaluation Workflow

Step 1: Visual Inspection of the Cartridge Case

Examine the exterior metal of the cartridge under bright, direct light, rolling each round between your thumb and forefinger to inspect the entire circumference. Look for active green or white oxidation, deep pitting, extensive tarnishing, and structural cracks along the brass or nickel plating. Minor surface discoloration or dull tarnish is typically cosmetic and safe, but deep pitting that reduces brass thickness or greenish verdigris inside the case mouth indicates chemical breakdown from corrosive primers or improper storage.

Warning: Never fire ammunition displaying deep structural cracks at the neck, shoulder, or base, as case-head separations allow high-pressure propellant gases to vent backward into the firearm action, risking catastrophic failure.

Step 2: Physical and Tactile Integrity Checks

Run your fingers along the overall length of the cartridge to check for dimensional anomalies, bullet setback, or primer anomalies. Measure the overall length (OAL) with a digital caliper and compare the reading against established SAAMI or CIP specifications for that specific caliber. Bullet setback—where the projectile is pushed deeper into the case—drastically increases internal chamber pressure upon ignition, while loose bullets indicate a compromised neck tension that risks powder contamination.

Pro-Tip: If a loaded cartridge rattles audibly when shaken gently, the internal smokeless powder has severely degraded, clumped, or broken down, altering the burn rate and pressure curve.

Step 3: Primer Inspection and Sealing Evaluation

Inspect the primer pocket area at the rear base of the case for structural deformation, puncturing, heavy rust, or missing sealant lacquer. The primer should sit flush with or slightly recessed below the base of the case head; protruding primers indicate excessive internal pressure or improper seating during manufacturing. Check for red, purple, or clear annular sealant around the primer edge; while missing sealant does not automatically ruin a round, its absence combined with damp storage conditions points to moisture intrusion.

Step 4: Olfactory and Destructive Diagnostic Testing

Smell the ammunition can or individual cartridges for unusual chemical odors, specifically a sharp, acrid scent resembling vinegar, rotting vegetation, or ether. This distinct smell signals outgassing nitrocellulose propellant, meaning the chemical stabilizers have failed and the powder is actively decomposing. If doubt remains regarding a specific suspect lot, pull the bullet using an impact puller, discard the powder and primer safely, and inspect the interior case walls for internal corrosion.

Ammunition Condition Reference Matrix

Common Ammunition Failures and Field Remedies

• Root Cause: Moisture intrusion past the primer or case mouth has contaminated the smokeless propellant, rendering it inert.
  
  
  • Actionable Fix: Stop shooting immediately, clear the firearm action, and check the bore for a stuck bullet or obstruction before chambering another round. Discard the remaining damp lot.
• Root Cause: Improper storage in extreme cyclical heat and humidity breaks down chemical stabilizers in nitrocellulose powder.
  
  
  • Actionable Fix: Quarantine the entire lot, verify lot numbers, and safely dispose of the compromised ammunition through a local hazardous waste facility or law enforcement agency.
• Root Cause: Extended exposure to petroleum-based gun solvents, penetrating oils, or WD-40 migrates past the primer or case mouth, chemically killing the priming compound.
  
  
  • Actionable Fix: Separate any oiled ammunition, wipe down clean exterior brass, and test fire a single control round only if contamination is strictly external and uncompromised.

Frequently Asked Questions

How long does ammunition last when stored properly?

Factory-loaded centerfire ammunition stored in cool, dark, and dry conditions with stable temperatures easily lasts for decades, often exceeding fifty years. Longevity depends entirely on environmental control; fluctuating humidity and high heat degrade primers and powder much faster than chronological age.

Can corroded ammo cause a squib load?

Yes, heavy corrosion allows moisture or cleaning solvents to penetrate the case and ruin the powder charge, creating a low-energy ignition. This weak ignition pushes the bullet partway down the barrel, resulting in a dangerous squib load that will catastrophic burst the barrel if a follow-up shot is fired.

Is military surplus ammo safe to shoot?

Much of the available military surplus ammunition is safe, but its safety depends on age, storage history, and whether it uses corrosive Berdan primers. Shooters must verify whether surplus rounds use corrosive salts, which require immediate barrel cleaning with water-based solvents to prevent rapid rust.

What should I do with bad or degraded ammunition?

Never throw live, unstable, or degraded ammunition into household trash or burn piles. Contact a local indoor or outdoor shooting range, a licensed firearms dealer, or your municipal hazardous waste disposal facility for proper local disposal protocols.

Does green tarnish on brass bullets mean they are ruined?

Light surface tarnish or verdigris on brass cases is often a cosmetic reaction between the copper alloy and cardboard packaging or leather loops. However, if the green corrosion is flaky, deep, pitted, or accompanied by a chemical odor, the brass is structurally compromised and must be scrapped.