When given the requirements for a new Marine rifle Stoner had a conf with the Commandant. He brought out the only thing that would survive some of the tests proposed, a 1" dia chromed steel rod. :)

But, if I had ordered a nicely polished blued barrel I don't think some simple bubble wrap would have protected the finish. If I were shipping barrels...I'd use the plastic tube my Shilen came in, and it was inside a 2" square, heavy duty, cardboard box.