Good ol UPS

I prefer USPS insured with tracking- as I don't have a FFL, if I have to ship either receivers or an entire shotgun, I will have my gunsmith friend Brad do this for me- his call as to UPS, USPS or Granny Grundy's Storm Door and Flying Circus MATS--

But my friend, unless you first "dope" the threads with PVC cement, the same Baggage Apes that can slice off the duct tape can also unthread the end cap and remove the barrels from your 16 ga. LeFever Optomisty and replace same with re-bar-- I am NOT a trusting guy when it comes to shipments of valuable items- so I take the extra and more costly route- if the threaded end cap on one end of the PVC tube has worked for you, I am most glad to hear that-