I started out thinking ammo cans were the way to go... & if putting them in zip lock bags, or vacuum sealed bags they should work great... however I prefer my ammo in plastic hinge top 50 round plastic boxes, & the ammo cans just didn't work for me... so I'll be selling a pretty large quantity at the gun show this next weekend...
BTW... I have a humidity controlled walk in gun safe & reloading room... because I also keep wood stocked rifles & handguns in the room, as well as reload in there, I keep the moisture level at 40-45% because the room is underground, it's very temperature stable & stays cool through the summer... I have storage benches built under the guns that are displayed on the walls... the benches hold a lot of plastic boxes of ammo or brass cases... the bottom of the storage benches have a 1.5" thick treated wood bottom, that sits on a layer of closed cell foam sill seal, that sits on the concrete floor of the room... there are 2 dehumidifiers & 2 sump pumps in the room, to insure the room is always dry... nearly all my ammo is handloads, & I keep several hundred loaded for each firearm, the rest of the brass is prepped & ready to go, stored in those hinge top plastic 50 round boxes... I've started to prime them, so I have less bricks of primers sitting around... my thoughts being, if I had 10's of 1000's of loaded handloads they could be a burden for my relatives... should they decide to get rid of some of it, after I'm gone... if I keep all I'd want to shoot in a couple years of each caliber, & components on hand for several reloads of each case, for future SHTF... then if they wanted to sell the primed brass or the components, it has more value than handloads...
BTW... IMO, as long as you are maintaining the humidity level, & keeping the temperature stabile, you can store your ammo in cardboard boxes if you wanted, & it would still be good enough for your grandkids to use