Bringing a carbon fibre tank through tsa customs

Hi has anyone been refused entry through customs while travelling on a plane with their PCp airgun . I have been told by the tsa that if you are taking an airgun through customs yo can't take a carbon fibre tank on checked baggage without the top of the tank being completely empty. That means they want to see inside the tank. I will find out if and how you can do this. 
 
Hi, jondon here. I emailed a.o.a and asked them if it's hard to remove the valve on the fx impact carbonfbre tank. They told me its loctited on and if it's not removed correctly , you can damage the tank and valve. I have not gone to Puerto Rico yet it's on the 7th of May but the gun is in a hard shelled case with 4 locks on it. I will have to send it by mail , but one of your subscribers offered me the loan of one which I thought was brilliant. Best wishes to everyone.