Huh? A DR comes apart just like a SxS and can be packed in a small readily-available box. If you don't want to buy a gun case which you would then pack in a corugated box, wrap the separae parts of the DR in a lot of bubblewrap and pack that securely in a stout corrugated box.
Corrugated cartons are rated by "burst strength" and, for example, boxes designed to ship clothing are much weaker than those designed for machinery or books. Get a box with a high burst strength, make certain there are several inches of padding around your gun parts and the box, strap the box with filament tape and seal it with gummed paper filament tape.
I ship my DR in a leather break-down case but even there I put bubble inside to prevent any wiggle (hence abrasion). I then wrap the case in more bubble and pack it in a cardboard carton sealed as above.
By the way, Jeff's Outfitters sells pretty nice leather take-down cases at very good prices. Not top-of-the-line but very nice and They protect your gun very well, as well as look nice.
