After a couple of shipping disasters with guns being shipped to me I insist that the gun is placed in a hard case then inside a cardboard box. I pay for the case and if ones not handy to buy for the shipper I ship them a case. I have several cases & boxes that have made several round trips. I make this part of the deal, no case, no sale.
Several years ago I sold my Model “T” 1903 Springfield and put it into a double rifle case. I cut out and put a piece of plywood and put that into the bottom of the case. I bubble wrapped the rifle put the case into the original cardboard box and shipped via UPS as the person I was sending to wanted. They, UPS, managed to drive the buttplate about three inches into the wood and destroyed the stock. They paid but it took some time plus a rifle they only made 100 of was messed up.
On the other side of the coin I bought a Prussian-Diamond-Daly from a fellow in New York City, he sent it, put together, loose in a box with several inches of movement both side-side & front-back, nothing in the box but the shogun. Arrived in perfect shape.