Why should I store my gun muzzle-down?

I am new to shooting, and I have been advised to store my gun muzzle-down in my cabinet. What’s the purpose of this?

GUN CABINET
Mike George
The idea is that, if you leave the barrels oily inside after cleaning with the idea that it prevents rust, oil doesn’t run back through the chambers and firing pin holes, and into the action.

An excess of oil there can gum up the works, and also soak into the wood and seriously damage the stock.

Most modern O/Us have internally chromed bores, which don’t need to be left oily after cleaning.

With plain steel bores, you can finish cleaning by passing through a patch, which is just damp with oil.

I usually store my guns with the barrels removed, but I do have rather more cabinet space than most folks.