I've seen the same thing a couple times with 22's at the range and with some pistols. It was like some kind of glint that only lasted a fraction of a second.

Now if you happen to reload a shotgun shell and only use the primer or a tiny bit of powder (oops), I can tell you from personal experience that you can see the shot and wad both wandering down range at such a very leisurely rate that any self respecting game bird would fall down laughing their head silly over.