Ammo cans with desiccant packs is the ONLY way to go!! No chance of the bags getting pierced, you can test the seals with water prior to loading ammo into them and lock them down!! I have several that I have used for decades and they still seal water and air tight!!
I have flown with weapons numerous times. DO NOT include ammo and a weapon in the same case!!!! These idiots freak out when they see the two together!!
If it is a "semi auto " pistol lock the slide open.
Working in Texas I have CC'd more there than at home here in LA. Never a problem.