Is it common to have to unpack a shotgun at the Post Office so they can inspect it before you ship it? The info I saw on the USPS website says it may be inspected, or you may be allowed to certify the gun is legal and not being shipped with ammo, etc and thus bypass inspection.

I'm going to be shipping a SxS that will be broken down, double boxed, wrapped and packed securely. It would be a pain to have to unpack everything at the Post Office and then repack and retape boxes. Just wondering what others experience with this is?