What about plastic cases, like Pelican or Nanuk? Most metal ammo cans don't seem to have a lock hasp, whereas these types of cases often do.
We use those for bulk transport in general, but ammo is still left in their factory boxes when in these cases, essentially its a glorified Rubbermaid container that stays water tight and wont fail under the weight.
This also allows us to stack better as we all have similar cases in the group and they interlock when placed in a certain way on each other, You can place two smaller pelicans on the longer rifle cases, etc.
The pelicans are part of the "range kit" they are restocked as required from the storage.
Home storage is industrial shelving unit inside a large closet, next to the safes, entire room is temperature/humidity controlled as it holds most of our outdoor gear and equipment.
Range Kit stuff being heavy goes on the floor/ first shelf under the large shelving unit. Rifle cases get emptied and go above the safes.
We ditched the foam in the rifle cases, all rifles go in independent soft cases and get tossed in the pelicans without any foam in them. The foam tends to hold moisture and there's a lot of it in BC outside of wildfire season.
Pistols are treated a bit different, similar small pelicans but they all have laser cut closed cell foam in them, very similar to the nanuk 6 UP cases, mags ammo and pistols all fit in in one their large respective cases, ammo boxes sit with them in their own open slots, it gets restocked as its consumed. (before any keyboard warriors come at me, yes this is still legal for storage and transport, pistols are trigger locked with the case being locked, and ammo storage regulations are met being in a locked case out of sight, it will be no different than the ammo being in the safe with the pistols, the CFO has confirmed this)
If you don't have the space for a setup like this, hopefully some version of it or an adaptation of it may come in handy.