Just and FYI to all in this dilemma, just go to the Dumpsters of your local gun shops and they are laying there in mass.. Also plenty of packing.. If you do not want to dig.. Go through the front door and ask them for one (or two).. you will be doing them a favor by minimizing their trash.
Also in shipping a gun one of the smartest things I have ever seen is using a tennis ball on the barrel to protect it from poking out the box.. and if you remove the bolt from the gun for shipping, make sure to attach it to the gun somehow. If its loose in the box and the box is torn, the bolt can be lost.