Ammunition Storage & Safety
Modern ammunition does not have a shelf life so much as a set of storage conditions. Keep it cool, dry and stable and it will outlast you.
Short answer Ammunition has no fixed expiry date. Kept cool, dry and at a stable temperature it fires reliably after twenty to fifty years; kept hot and damp it can degrade within a few. Storage conditions decide it, not age.
- Target temperature
- Below about 70°F, stable
- Target humidity
- Under 50–55% relative
- Best container
- Sealed steel can, intact gasket, live desiccant
- Realistic life
- Decades, properly stored
Does ammunition go bad?
Not on a timetable. A modern centrefire cartridge is a sealed metallic package: brass case, seated primer, smokeless powder and a bullet, often with sealant at the case mouth and primer pocket. Left alone in reasonable conditions nothing in that assembly decays quickly.
Ammunition kept cool and dry routinely fires after twenty to fifty years, and surplus from the 1950s still shoots. Ammunition kept in a hot, damp shed can deteriorate noticeably in a handful of summers.
Manufacturers who publish a figure typically quote ten years, which is a warranty position rather than a physical limit — the period they will stand behind without knowing how you stored it.
The three things that matter
1. Heat, and especially changing heat
Sustained heat degrades smokeless propellant and can slowly alter the pressure a cartridge produces. Worse than steady warmth is cycling: a garage swinging from freezing to 120°F across a year drives repeated expansion and contraction, which works at seals and draws moist air in and out of the case.
2. Humidity
Moisture is what actually ruins ammunition. It corrodes brass, creeps past primer pockets and case mouths, and produces the green verdigris you see on badly kept stock. Under about 50–55 per cent relative humidity, corrosion effectively stops.
3. Solvents and fumes
Ammonia-based cleaners, bore solvents, petrol, fertiliser and pool chemicals all attack brass; ammonia in particular causes season cracking. Never store ammunition in a closed cabinet with open solvent bottles.
Sunlight is a fourth, smaller factor. Ultraviolet light degrades polymer tips on tipped hunting bullets and fades box labels until the lot number is unreadable. Keep it dark.
Where to store it, and where not to
| Location | Verdict |
|---|---|
| Interior closet | Best. Climate-controlled, dark and stable. |
| Conditioned basement | Good if dry. Run a dehumidifier; keep cartons off concrete. |
| Interior gun safe | Good with desiccant or a rod dehumidifier. Safes sweat when the room does. |
| Unconditioned garage | Poor. Worst temperature swings in the house, plus solvents and fuel. |
| Attic or loft | Avoid. Often well over 130°F in summer. |
| Shed or outbuilding | Avoid. Unheated, damp and least secure. |
| Vehicle | Avoid beyond short trips. Cabins exceed 150°F. |
Containers, cans and desiccant
- Keep the original boxes. They separate rounds, prevent primer strikes and carry the lot number you need if there is ever a recall.
- Steel ammunition cans with an intact gasket are the standard for bulk storage. Check the gasket is soft and unbroken — a perished seal makes the can no better than a cardboard box.
- Put desiccant inside the can, not outside, and recharge it. Silica gel that has absorbed its fill does nothing.
- Plastic bins are organisation, not protection. Most are neither airtight nor opaque.
- Avoid sealed plastic bags. They trap whatever humidity was in the air when you sealed them, right against the brass.
Should you shoot old ammunition?
Inspect it rather than guess.
Generally fine: bright or lightly tarnished brass, bullets seated straight and firm, primers flush and unmarked, no smell when you open the box.
Do not fire it: green or powdery corrosion, cracks at the case mouth or shoulder, bullets that move under finger pressure, primers pierced, proud, sunken or leaking dark residue, or a sharp acrid smell from the carton.
Two further cautions. A cartridge repeatedly chambered and ejected can have the bullet pushed back into the case, which raises pressure sharply — set those aside rather than rotating them back through the magazine. And genuinely old military surplus may be corrosively primed, which is safe to shoot but demands the rifle is cleaned with water-based solvent the same day.
If you are unsure, do not fire it. Dispose of suspect ammunition through your local police department, a range that accepts it, or a licensed disposal service. Never put ammunition in household waste, never burn it, and never disassemble a live round without the tools and training.
Safety and access
- Store ammunition where children and prohibited persons cannot reach it. Several states impose a legal duty, and a locked container is cheap insurance either way.
- Keep ammunition and firearms in separate locked containers where circumstances allow.
- Do not keep loaded magazines loose in a drawer — feed lips bend and a dropped magazine can strike a primer. Magazines stored loaded are fine; spring fatigue comes from cycling, not static compression.
- Keep powder and primers apart from loaded ammunition and from each other, in the manufacturer’s original containers.
- Tell your household where it is and that it is off limits.
Common questions
How long can ammunition be stored before it goes bad?
There is no fixed expiry. Kept cool, dry and stable, modern ammunition fires reliably after twenty to fifty years, and well-preserved surplus from the middle of the last century still works. Kept hot and damp it can deteriorate within a few years.
What is the best way to store ammunition?
In its original boxes, inside a sealed steel can with an intact gasket and a live desiccant pack, in a dark interior space below about 70°F and under 55 per cent relative humidity, away from solvents and ammonia.
Is it safe to store ammunition in a hot garage?
Not dangerous, but it is the fastest way to degrade ammunition short of soaking it. Garages cycle hardest between seasons, which stresses seals and draws damp air in and out of the cases, and they usually hold the solvents and fuel that attack brass.
Is it better to store ammunition in plastic or metal?
Metal, if the choice is a gasketed steel can against an ordinary plastic bin — the seal and the opacity are what matter. A genuinely airtight, opaque polymer case with a gasket does the same job.
Is it okay to store ammunition in sealed plastic bags?
Better than nothing but worse than it looks. A bag seals in whatever humidity was present when you closed it and offers no physical protection.
How long can ammunition sit in a magazine?
Indefinitely as far as the spring is concerned — springs wear through cycling, not from being held compressed. The real limits are dust and lint, and the top round being chambered and ejected repeatedly, which can drive the bullet deeper and raise pressure.
Is it safe to shoot twenty-year-old ammunition?
Usually, if it was stored properly and inspects clean: bright brass, firm bullets, flush unmarked primers, no smell. Reject anything with green corrosion, cracked cases, loose bullets or leaking primers.
About this page
Written from manufacturer storage guidance and SAAMI’s published recommendations on storing and handling sporting ammunition. General guidance only — follow the instructions supplied with your specific ammunition and firearm. How we source what we publish →