The problem becomes: how do you know you have a good seal?
I used to store munitions components in drums, but those had humidity indicators on them that were checked periodically. I can assure you that sealing those drums is "hit and miss." Those drums were also stored inside Butler buildings, out of the weather but not climate controlled. Still the condensation built inside of them (some of them). The method we used to seal them: Snug the closure ring bolt, tap around the edges with a mallet, 2X4, etc. Snug some more, tighten, repeat...until you're confident it's as good as it's gonna get. Check on your parts periodically, and don't get lazy about it.