Mishap

I'm about to watch this.  An amateur gunsmith made a modification to her pistol and it went off in her holster.  That's all I know as of this moment. 

But I bet I know what it is. 

My guess is, 1911, and the hammer and sear engagment.  It was done in such a way that the sear was on the hammer hook, but when pressure was taken off the trigger, it didn't go back into a 'rest' state.  On of the hardest thing to test for. And a slight jar will let it go. Bang in the holster.

Let's see, back in 10: