I came across these pictures of me shooting a friend's new Brian Barker rifle(pictured below).  In the first picture you can see the pan just lighting off.  The second shows the gun firing, and the pan smoke has started to rise.  If you look close you can see two puffs near the pan.  One small and one large.  The first is the pan lighting, and the second is the main charge blowing out. They aren't far apart.  He took these pictures with a smart phone on rapid fire.  They are one frame apart.  This rifle is really quick.  I tried to zoom the pic to see if I had time to close my eyes, but I can't quite tell.  I don't believe I had time.