Do Matchlock Guns Work in the Rain?

Do matchlock guns work in the rain?

Because the powder is covered, then most of the time the gun will shoot. However a wise commander will take into account the likelihood of misfires and the increased smoke as water vapour holds on to the spent gunpowder.

Because the powder is exposed to the elements in the moments before shooting, rain or strong wind can cause the weapon to misfire.

During the warring states and following eras there were devices that protected the powder to a greater extent. However, the flash pan cover was also useful in keeping the gunpowder dry.

Gun powder; koyaku (火薬)

Flash pan; hizara (火皿)

Flash pan cover; hibuta (火蓋)