Storing ammo in cans in the attic - thoughts?

I think it'll be fine. I decked over my attic some time ago. I figure it spread them out over a wide area it should be fine.

You can buy oxygen absorber pouches on Amazon for cheap, 100 for $10. I've got ammo cans full of M855, primers, and brass prepped for reloading that have 3 of those little pouches in each can. Those cans have been in a non-air-conditioned garage for almost a year, opened them recently just to check and not a spot of tarnish on anything. They could sit for decades like that and be perfectly fine.