Unless required by local statute put ammo in ammocans with a desiccant pack and store stacked against a wall in a closet or under your bed or behind furniture. It'll be fine.
Just use common sense. I still have surplus '06 from the fifties ( black tip) that is still viable. But I don't store it in the commode tank either. I did have some 7.62X51 surplus from the late eighties that was complete junk because of storage conditions in a place with too much moisture. Turkish headstamp if I recall.
FWIW, mine is in original boxes or mags, stacked inside a welder's box in the basement. Temp is controlled to never go below 55, the basement is dry all year and stays fairly cool in summer. (Except trap ammo stacked on a shelf in the same area, gotta be able to grab and run on shooting days.) There's some vintage milsurp 30-06 (50s), 7.62X54R (40s) that has been around a long time with no degradation in the box.
I'm still new to this but if your really into it maybe one of those fiberglass storm shelters? Or if you have an old root cellar?
In my experience, most reasonable efforts to keep ammo dry and away from real extremes- will yield usable stock. I have shot ammo that has been sitting for 10 years is an uninsulated/uncooled/unheated tack room and have not experienced any problems. I keep ammo in old usgi ammo cans with one desiccant pack and stored near the floor. I am willing to bet that those old spam cans of surplus ammo that are all the rage now-a-days have not been treated like a delicate science experiments. I live in the Southeast USA temps from 100 degree summers to low teens in the winter.
I have an ammo story of my own that may stir the pot some I sometimes say that I grew up with an army base in my back yard, and that's kinda true. The ranch that I grew up on in my early years was backed up against a huge training center in the northwest. Matter of fact, Audie Murphy's "To Hell and Back" was filmed there-at least in part. Anyway, being the 150% boy that I was, I would sneak on post via horseback and later on, via a KE125. The memories of out running/ hiding from the MP's still bring a smile to my face.. Bottom line, I knew that base better than most posted there. One day when I was hunting rabbits on base, I saw something that appeared to be " leaking" from the side of a dry wash. when I got up to it it was a pile of ammo cans... Most were severely rusted, and as I dug I found more and more,along with a bunch of old C-rat cans. It took me 3 trips all night to bring home my booty. I recovered several cans of '06 blanks in M1 clips, cans of belted '06 live and blank. One wooden/wire crate(mostly rotted) full of cans of M1 ammo in bandoleers. I still have a couple of the belts of blank ammo hanging in my reloading room. Now I DO NOT suggest anyone do this, but I burned up all that ammo in my M1 with VERY few duds. The cans that were too far gone(rusted through) I left, but the ones where the ammo looked good I used. Still have some clips that I use. I can only assume that this stuff was leftovers from a training exercise in the 50's and got buried instead of being humped back? As far as storing ammo, I store it in ammo cans with good rubber seals, packed with desiccant packs layered through out. If the ammo is to be buried, I vac seal in stripper clips/M1 clips where possible. All ammo has primer pockets and around case mouths sealed with clear nail polish beforehand.
I've fired pistol ammo that was left in my jeans and washed in hot water, and also properly stored 1909 era .303 British that is to this day, sure fire. Store it in USGI cans with dessicant, moderate temps and it will be fine
