Why would anyone store ammo in the safe?
Is this to protect the ammo against theft or nefarious use by children?
It seems like one of those locking sheet-metal gun cabinets might work for such needs at a -FAR- lower price point.
I keep my ammo in an antique piece of furniture -- I don't know what you'd call it. But it's go a door on it, two shelves and a big drawer and the dang thing must be a hundred years old or more. It's perfect for ammo... but if I didn't have it, I'd just pile the stuff up anywhere that's orderly and has a door over it so you can't see it through the window. Let's say a closet with a solid bunch of shelves. That's where I'd likely end up.
A gun safe is prime real estate and I definitely don't waste that precious space on a consumable commodity.