Keep your powder dry!  The number one killer of ammo is moisture but 
I discovered a good way to store bulk ammo in manageable packets.  Not only is Mylar flexible, but it's waterproof and light-weight.  Add a desiccant before sealing and increase ammo life by decades.

I recently moved 1000 rounds of 9mm from a bulk box into mylar packages with 50 rounds each.  Now I have a waterproof container to put in bug-out or range bags.    I like how flexible Mylar is for sealing a specific number of cartridges into a box for specialized needs.  

Check Out ReadySquirrel.com for more articles on Beans and bullets.

If you are on the hunt for Mylar bags and Oxygen absorbers check out the Ready Squirrel affiliate link on Amazon. Full disclosure, I do get money for beans and bullets if you purchase from this link.

PackFreshUSA: Five Gallon Genuine Mylar Bags (19" x 28”) - Individually Sealed 2000cc + 500cc Oxygen Absorber Packs - Rounded Corners - Odor/Smell Proof - Heat Seal - Long-Term Food Storage - 6 Pack- https://amzn.to/2WnqAum