It's CBP form 4457. Post #7 has the link.
I don't carry the Pelican case for plane crashes (that's absurd). I carry it for protection on the ground. It is never checked baggage. I will bear the weight when hand carrying and I will judge what I want to carry as anyone will do. I mentioned that I have not had security or customs issues except once with US Customs with a Pelican case to answser the OP question. The Customs agent wanted to know if 1. I was a professional (seemed to be either a revenu generating question or a lead in to the next question) and 2. If I had purchased the camera equipment abroad and asked if I had registration or receipts. I registered it after the trip in case I was ever asked again. It's easy. There is a regional airport nearby Denver metro that has a CBP office so I don't have to go to DIA.
So this (the US Customs challenge) has happend in the past 30+ years and is still a US Customs issue.
I don't carry the Pelican case for plane crashes (that's absurd). I carry it for protection on the ground. It is never checked baggage. I will bear the weight when hand carrying and I will judge what I want to carry as anyone will do. I mentioned that I have not had security or customs issues except once with US Customs with a Pelican case to answser the OP question. The Customs agent wanted to know if 1. I was a professional (seemed to be either a revenu generating question or a lead in to the next question) and 2. If I had purchased the camera equipment abroad and asked if I had registration or receipts. I registered it after the trip in case I was ever asked again. It's easy. There is a regional airport nearby Denver metro that has a CBP office so I don't have to go to DIA.
So this (the US Customs challenge) has happend in the past 30+ years and is still a US Customs issue.