Blue Tile Spook
Master
Bad idea. Dont give them any reason to suspect you own a firearm. All it will do is target you for a "random" vehicle inspection.
I can only speak for the companies that I have worked for in the past. They were honorable and upfront about any rule changes so for me to walk into H.R. to ask a question was not a large ordeal. It was also well known amongst the employees and most of management that I owned firearms even though none ever asked me if I was carrying on the property or had any firearms in my vehicle.
At my last job, we were not allowed, by the rule book, to carry any knives of any sort. Because I helped the maintenance guys a bit when I was on 2nd shift and ended up running the 3rd shift for a year, the rule was waived for me.