He appeared to place an automatic in his mouth and fire. There was blood. I'm not sure how the are going to play this out. I mean even it was a blank and a squib pack the packing from the blank would be enough to penetrate the roof of the mouth palate and he should be dead from that.
So again I'm not sure where they are going to go. I do really enjoy the way the Moriarty character is played. There was a Sherlock marathon on our local PBS affiliate last Sunday so I watched from the Richenbacher Falls episode through the mind palace extortionist.