Indeed I did.You will notice that the Title of the Post is "OKLAHOMA'S RESTRICTIVE KNIFE LAW drop off the books today."
You quoted 18 U.S.C. 930. U.S.C. stands for "United States Code" aka Federal Law.
Most everyone remembers they're carrying a firearm before entering the post office, but a knife... maybe not so much.
Just trying to be helpful. Apologies if I was out of line. Apparently I have no idea where the line is.