ld1,
yet another way for them to mess with us gun fanciers,eh?
Do you mean a box to put the rifle case in, or just a cardboard box?
If I was buying a double rifle,I hope the seller wouldn't pack it in just a cardboard,no offence meant of course.I wonder if a local gunshop might have one that was bound for the dumpster after serving its initial purpose?.
If its to put a case into, they are easy enough to make if you find an old appliance box,plus some good shipping tape (not duct)
good luck
franc