Glad to see a lot of common sense advice is being offered here.
First and foremost, contact your local police department. And become friends with them. Ask them for advice prior to scheduling any filming.
One thing to ALWAYS keep in mind, whats acceptable in one community/jurisdiction may not be okay in another.
In my area, I am allowed to paint the orange tips or replace them with the real thing. But I am a film armorer and also have contacts in Law Enforcement throughout Southern California, and can make a call to notify them my company is going to be armoring a set. They know I have stringent safety rules, and I have not had a problem yet.
Case in point:
Working a student film about a month ago, the director failed to pull permits (I found out after on set, though they said they had them).
LAPD (4 cars) shows up code 3 to the area we were filming. But because of my safety briefing, all the actors knew exactly what to do when I called "WEAPONS Down!" They all put their hands on their heads, before the first officer even put his car in park. All said and done, we were allowed to finish the scene, because I showed the responding officers they had nothing to fear. The sergeant and I joked afterwards, and showed him the rest of what I had in the truck. Needless to say, eyes got big as dinner plates, and I was given several business cards from them.
But that is all about doing the homework in pre-production. For those interested, I will repost an article I wrote regarding this very subject about a year ago in another thread.