I once had an agent at DAL in 2016, I think, try to claim my rifle case with two padlocks wasn’t secure enough as they believed it could be pried open.

After showing my numerous accumulated firearm declaration sheets in the case showing Delta had accepted this case over 14 times already, the agent relented.

That was the only time I had any trouble and continue to use that case on trips as recently as 6 months ago.