Ammo Storage: What Actually Ruins Rounds
It's not age. Ammunition that's been kept dry and out of the sun will outlive you. It's moisture, and moisture is the one variable you actually control.
I've pulled apart .30-06 from the 1950s that still went bang, primers intact, powder still burning clean, because it sat in a sealed can in a dry basement for seventy years. I've also seen a case of 9mm go green with corrosion in under two years because someone left it in an unheated garage in a cardboard box. The difference wasn't the ammo. It was the box.
Moisture is the actual enemy
Primers and powder are both sensitive to moisture, not time. A sealed ammo can with a rubber gasket keeps humid air out entirely; a cardboard factory box does nothing once it's been opened and closed a few times. If you're storing more than a range trip's worth of ammo, it belongs in something with a gasket and a latch, full stop.
Temperature swings matter less than people think
There's a persistent worry about ammo "cooking" in a hot car trunk or freezing in an unheated shed. Within any range a person actually lives in, this isn't the problem it sounds like. Extreme, sustained heat over years can slowly degrade powder, but the kind of daily temperature swing a garage or car sees is not the failure mode. Humidity that comes with those temperature swings, condensation forming as the air cools overnight, is the actual risk, and it's a moisture problem again, not a heat problem.
A dehumidifier earns its space
In a safe or an enclosed cabinet, even a good seal on the ammo can doesn't stop humidity from building up in the surrounding air every time the door opens. A rechargeable silica canister sitting in the safe pulls that moisture out continuously without you doing anything, and it's rechargeable in an oven or a wall outlet instead of needing replacement packets. This is the five-dollar habit that actually matters more than a hundred-dollar can.
Storage and security aren't the same problem, but solve them together
A dry ammo can does nothing to keep ammunition, or the firearm it feeds, away from someone who shouldn't have access to either. A quick-access safe for the gun and a locked cabinet for ammo cans solves both problems in the same footprint, and it's worth setting up before you have a lot of either to store rather than retrofitting later.
What I actually check twice a year
Twice a year, I pull a few rounds from the back of the oldest can, not the front, and look them over: green or white corrosion on the case, a loose or tilted primer, any powder residue where there shouldn't be any. It takes ten minutes and it's the only real early warning you get. If the ammo at the back of the can from three years ago still looks like it did the day it went in, everything in front of it is fine too.
Ready to shop? Browse Ammo Storage & Cases.