I store mine without the plug. That keeps the bore oil from seeping in. I put the ML muzzle-down for a few days with the breechplug barely started- then turnthe ML over & unscrew/remove the clean, dry plug.
My breechplug then goes in a small sandwich baggie - then I push the baggie thru the muzzle-end of the ML's attached ramrod for storing purposes. It dangles from the ramrod end in open view.