I'm not disagreeing with your statutory exegesis. What I'm telling you are the facts on the ground. If caught carrying any weapon (knife, pepper spray, collapsible baton, striking implement, gun) in a designated "federal facility," you will be charged. Whether it is as a violation of 18 USC 930 or 41 CFR 102-74 will be of cold comfort to you, and of little moment to anyone else except, perhaps, your defense counsel.
Once, back in the pre-9/11 days, I had to pass my bag through the x-ray, which promptly disclosed the presence of a commonplace household steak knife - with which I planned to eat some leftover steak for lunch. They pulled it, pondered it, called over a superior before waving me through.
A much more recent case, to which I alluded in my previous post, didn't end quite as pleasantly. I was let off "easy" because I was one of "theirs," had a spotless 16-year record, and had some superiors willing to go to the mattresses for me. But some pretty heavy hitters wanted me arrested, criminally charged, and fired. I understand the discussions were quite . . . animated. Fortunately for me, the hardcore hoplophobes didn't carry the day.
"...A humble and contrite heart, O God, thou wilt not despise." Ps. li
"When law and morality contradict each other, the citizen has the cruel alternative of either losing his moral sense or losing his respect for the law." —Frederic Bastiat