"I assure you that TSA, the FAA and the airlines do legally consider bp replicas to be firearms and require they be transported like any other firearm"
(Because neither the TSA nor the airline had the answer close at hand).
Bear in mind please the distinction between carriage aboard the jet (hand carry) and shipment as cargo (in your bag). The former is obviously an issue. The regulations concerning the latter are the question at hand.
Really the only question, to me, was if I was REQUIRED to declare it as a firearm in my baggage and was REQUIRED to have it locked in a container by a non-TSA lock, or if was not legally required for me to do so.
In any event it was so easy to simply handle it like a modern firearm that it was barely a 30 second delay at check in. I will be doing this far more often now that I've done it once.