Ask the RFD is the best advice. They can access courier services that are not available to the general public, for example a lot of them use TNT who won't take domestic trade.
It's normally a next day service, just avoid sending on Fridays as that means your pride and joy will spend the weekend knocking around some warehouse or depot, with an extra 48 hours of at-risk time. If you miss the Thursday pick up, tell them to wait until Monday, for Tuesday delivery. My local RFD will never ship a rifle or shotgun on a Friday.