Absolutely true. In the 90s, I went to a regional shooting competition with a handful of other high school kids, and we brought firearms onto the plane.
I'm sorry, but you are just wrong. The relevant US code is at https://www.law.cornell.edu/uscode/text/49/46505 -- it's been in place since the 50's. Security screening to detect weapons has been in place since the early 1970's, after a rash of hijackings in the late 60's. You must be mis-remembering.
