Mine are also in the basement and made a rack on one wall for them. Was able to inspect easy. But theft here is so bad I found myself buying a safe with maybe 2/3s of them in the safe with the rest chained to the wall. Craps one has to do this but maybe help in case of a fire.
But have same concern with using safe and I have had in my life a gun get some rust on the outside. But that was my fault for the way I took care of that rifle. Did wipe off with fine steel wool and oil. For the most part have not been over the hill on cleaning and wiping off before putting away. Main concern when bring into a warm room with the rifle coming from the cold outside. So will take, clean and wipe off after it sat for some time. But have had no problems with rust that I can see over many years with just some normal regular care. Now and then will wipe down and run a rod through the bore. Can buy a can to put in safe to help protect. One needs to INSPECT on a regular bascis to make sure one catches it before it starts.
Legion has a number of m-1s kept in a safe. Every time they use and bring back they just put back in the safe after running blanks through them. No one cleans or even wipes off. So every now and then, like maybe once every two years, me and another guy go take apart and clean but have seen no ill effect on the rifle. Bore always appears okay. But that's with the eye and not maybe inspected the way they should be.
They had the Krag rifle since the 1920s at the cabin with the same occasion care (for the most part none). Did sell and I got one. Bore looks great. Outside no pits but looks well used. Need to shoot to see.
Bought a model 73 this summer made in 1889. Outside looks good but not the bore. Cleaned and then cleaned and then cleaned some more. Shot at box at 25 yards. Group was bigger than a volley ball. Tried again and same. Cleaned some more and tried again and the same size group. Cleaned and tried again with same results. First time I every used black powder shells. After cleaning a few time I was done cleaning after using black powder shells. And I thought Winchesters were the best (rifle seen the wrong kind of care). db
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After cleaning one day on my safe that was rated at some kind of burn protection, I found there were a couple of holes in the floor under the mat of the safe already. db