On my two trips to SA flying on Delta, they have never asked me to do that. They were more concerned with my rifle being unloaded and the forms signed. Luck of the draw I guess.
Same hear with Delta. All they have done is asked if had ammo and if was under 11 lbs., they have never weighed it.
Qatar tho weighed at every check in. One time they had me remove ammo from the case and just weigh the ammo itself.
This was in Houston