I use a dehumidifier to regulate and reduce humidity, water vapour in the air can cause rust. set-up a temperature & humidity guage in the storage room.
A dehumidifier will reduce humidity when needed, while measuring humidity levels and adjusting the dehumidifier to come on and turn off automatically.
I have my dehumidifier setup in my work shop in the basement protecting my work tools for rust. I have another dehumidifier in an adjoining room where all my outdoor equipment is including gun cabinets. The extra dehumidifier is only used when absoulutely necessary to reduce high levels of moisture vapour in the air. I have experienced damp and sometimes leaky basements with 2 different homes, and dehumidifing for moisture/water vapour in the air is a must.
Like Tom I wipe down my firearms with a cloth soaked with oil and leave a film. Todays firearms are extremely rust resistant. Stainless receivers & barreled rifles, camo coated shotguns...its the blued metal barrels and recievers surfaces that need to be maintained wiping them down with oil, including wooden stocks to avoid cracking due to excessive dryness.
With almost a life time of experience with firearms, I highly reccomend cleaning your firearms promptly after hunting/shooting.
Last quote, Say your out hunting ducks or deer in the drizzley rain in november...once your done and get back to your vehicle, dry off your firearm with a dry cloth/towel before putting it in the case, then I lay mine on my fully opened gun case and give it a spray with WD40 top to bottom both sides..then when I get it home take it out of the case and get at it, Take it a part, moisture finds its way in and get er cleaned.
Cleaning your firearms right after use is key, barrel bores included.. to prevent gunpowder corrosion, especially muzzleloaders..
I hope that helps some of the new shooters reading..take care of them and they will last forever.