Over the years the Army experimented with many forms of long term preservation. What they were trying to get to was dry preservation making the object ready to use when unwrapped. Some parts were preserved several times in different packaging.
One method was the use of VCI paper (Volatile Corrosion Inhibitors) the paper was treated with a chemical that gave off vapors that prevented rust. That's the paper wick in the bore.
The M1 I got in 1987 was shrinkwrapped to a heavy cardboard sheet with wooden block at each end that were cut out for the butt and muzzle the whole works was in a heavy cardboard box and it was shipped to me by registered mail delivered by my rural mail carrier. While I saved all the paperwork, I didn't save the shipping box
Maybe Armorer will jump in here as he has real world experience with the Army's preservation methods
"Fat's all right as long as its not from the neck up" Major General Hunter Liggett circa 1919"
Looking for sympathy, it's in the dictionary, right between SHIT and SYPHILIS" ...... Tom Jisa.... (My father-in-law) circa 1965.. or, if you prefer the more classical......Manus haec inimica tyrannis Einse petit placidam cum liberate quitem. (This hand, enemy to tyrants, By the sword seeks calm peacefulness with liberty)... Algernon Sidney.. (British patriot) circa 1665...