My employer only has 2 written policies: Sexual Harrassment and Illegal Drug Use. There is no written policy regarding weapons of any sort. There is, however, small lettering on the bottom of exterior doors that say "No Weapons Allowed." I work for a company that, while we have over 1000 employees worldwide, only have around 100 in our home office here in Dallas. My immediate supervisor is the Vice President, and I have an open door to the President.
When one of the sheep in staffing decided that she was worried that we don't have an actual policy banning handguns on the premises, HR was forced to consider the issue. Being the resident "gun nut," the Pres, VP and HR queen called me in to get my thoughts on the issue. The Pres started it out by telling me not to tell him if I carry to work. He then asked what my thoughts on banning guns from the premises. I told him that if he did that, he would be taking responsibility for the safety of all the employees, since he'd be taking away their ability to choose to defend themselves. I told him that my wife has specific instructions to sue my employer if I'm disarmed and killed on premises. He stared up at the ceiling for a minute and asked if there's anything good about banning guns. I told him he's only disarming people that follow rules. I asked him if someone's going to shoot the place up, if he thought that they would concern themselves with an HR policy.
Later he called me to tell me that their insurance company, as well as 2 others they called, would not insure them if they did not have a weapons policy.
Basically, now we have a don't ask, don't tell policy. They left the lettering on the door, but they have not put an actual policy in writing. The VP (who had an FFL and reloaded to put himself through college but doesn't shoot now) told me that the Pres said no one's going to get in trouble for carrying, but if done right, no one would know anyway.
I think that's about the most you can expect from an employer these days. I think the only thing that stood between me and an official OK to carry was the insurance company.