I missed 3 and 7. I think 7 (the blown-up black powder revolver) could as easily have been a barrel obstruction -- I watched the video several times and I couldn't detect anything coming out of the muzzle.
I heard the round hit the target. Also, from what the observers said, he hit it.
The lady who had to pull the trigger twice was my last one, I answered hang fire because I knew it wasn't a squib, failure to feed, or double fire.
I would have termed it a 'failure to fire', as it took a second strike of the firing pin to set it off.
I was really guessing on the stovepipe - I knew it was one, but I've only ever heard of stovepipe - never horizontal or vertical. Same with the black powder - I flipped a coin between 'old powder' and 'wrong powder', but ended up going with 'wrong' because old could be considered wrong, and 'old powder', properly stored, isn't normally a big deal.
Anytime the gun blows up a short fire is a good guess as to culprit, as long as it's not the first shot...
10/10