I've worked at Thompson Center for 2 3 year periods, once in the 80's and again 01-04
Not even a urine test, it was no different than any other Machine shop, (may be different since S&W bought them ) I understand that Ruger is the same way.
Sig on the other hand, does a background check and has Security guards on the doors, you go through a metal detector every time you go out side for break.
There is no requirement to notify Police of any thing. The only industry standard is "can they do the work they are being hired for"