I use an old 5 drawer Steelcase File Cabinet. It locks and is very sturdy. The deep, wide drawers let me store a LOT of ammo, and it allows easy sorting too.
For bulk ammo, I just stack the cases up in a back closet. I made low shelf out of treated 4 X 4, and boy you can get a lot of 7.62 X 39. 5.56 X 45 and 7.62 X 51 in a closet
