In a video I found at The Daily Caller, the answer is obvious: not very dangerous at all, if the ammunition isn't actually in a firearm's chamber.
The most informative video you'll see this week, probably. It's long at just over 25 minutes, but is worth every minute.
I hope all of you gun bloggers out there will put this video up on your own blogs, and share it as widely as possible. Probably Hollywood could use this information, too, since it defies every Hollywood notion of guns and ammo that there is.