Desiccant is your friend. The cardboard or bandoleer retains moisture. Some considerations.
Stamdard unit = 1oz = 28 grams (customer support from a manufacturer).
10 grams can cover 1500cc for a volume reference.
1500 cc apporx 91 cu. inch.
Fifty cal ammo can 6x7x11.5 = 483 cu. inch empty
483/91 = 5.3 10oz packs empty. Industry doesn't consider volume but grams of water at two specific tempuratures as far as I can tell. I can't measure this.
I prep the can for a week to absorb water from the cardboard/bandoleer then replace with fresh with a 3x5 card with info and date packed. I use 20 gram for a 30cal can, 40gm for 50cal and 60gm for a fat50.
I hope it's enough.
I also bought a Linco ph testing pen. Some cardboard (foreign) can be acidic. 1990s Lapua for example.
Vaper Control Inhibiter VCI bags/chips are another option. Rated 5 years.