Colorado is an open carry state, meaning you can walk down the street with a loaded gun in a holster.  That said, there are a couple situations to be aware of.

  1. Colorado is not a "pre-emptive" law state.  This means that city governments have the right to make a law restricting open carry.  This does not affect licensed concealed carry, but Denver, for instance, does not allow you to open carry.
  2. If someone becomes concerned, from seeing your firearm, and they call the police, you can be charged with menacing.  The commission of the crime is based only on how your firearm made the person feel, not your intent or if others were alarmed too.
  3. You can not carry (open or concealed), and consume any alcohol or intoxicants.  You can legally carry it in a bar, as long as you are not drinking.  Technically, this law probably includes things like cough syrup too.

NOTE: These are merely a few of my understandings of the law.  Please seek professional legal advice before relying on their accuracy.