I have travelled to, from and within the USA - probably up to about 30 or 40 Int & domestic check ins combined by now.. with firearms.

Never had a problem. My experiences are much like the one described by the OP... quick and professional. Don't recall the case ever being "unpacked" however. Maybe not always the "friendliest" (except in DEN where the TSA guys we dealt with, while retaining their professionalism, were a HOOT!) but I'm not really sure that is grounds for even a minor complaint....

I have carried a powder thrower in my hand luggage (I had been loading/shooting Pyrodex loads that trip - a Black Powder substitute if that helps) and it was pulled out and wiped.. I thought THAT swab would cause the machine to react.. but no... sporting propellant residues clearly are NOT a problem (IME anyway!)

The screener I was dealing with was quite confused by this device of mine so she (quite rightly IMO) followed "procedure"..... another screener several machines away must have been a handloader.. he kept trying to tell her "It's OK, it's just a powder thrower!"

On a LESS happy note.... We had always been told that transiting - even NYC - was not a problem as long as we carried the registration confirmation for the competition we were on our way to....

Not sure I would now feel safe doing so.... If US citizens are being harassed like this.. what chance has a foreigner got?

Simple (but possibly more $$$) solution of course... avoid such transit citys....