I would assume this was armslist and not craigslist. not saying you can't get away with posting a gun for a short period, but why go through the hassle? Nobody is going to craigslist looking for guns, so you probably wouldn't sell it. Armslist is just as free.
I have bought and sold about a dozen firearms on Armslist, everyone was really nice. I always have them meet at my office on a workday, I can see them pull up through the window, and they don't know which office I work in. So I feel that gives me a little bit of an edge, I tell him to call me when he gets there and I can who pulls up. I know just seeing someone doesn't mean they aren't going to rob me, but it helps. And, I have the advantage of being around my co-workers, close to a door and knowing the area. Plus, theres lots of obvious cameras