I purchase ammo cans several at a time. .30 cal and .50 cal cans. Pistol cartridges in .30 cal cans and rifle ammo in the .50 cal.
Example: Load approx 1000 rds of .38spl 158g SWCs. Drop them loose in the can. When full seal the lid, wire it shut, and stencil on what caliber, load info, and date. I stack them in the closet of my bedroom. House is always moderately cool. Never gets over about 80 degrees. And there is little moisture, though that shouldn't be too much of a problem.
Then I also use the tall .50 cal cans for storage of misc. stuff. Mostly anything that may be of use should SHTF.
Two Combat Tours
Criminal Justice Major.
15 years of shooting under the belt
Collection of both modern and antique handguns and rifles
STILL A YOUNG MAN WITH LOTS OF TIME