Your knowledge of firearms does not necessarily make you proof against human error or folly by others. I was at a performance some years back at a veterans hospital. A performer I knew brought several volunteers on stage and one was handed a pistol.
As soon as the weapon was in his hand he pointed it at the audience and pulled the trigger rapidly, emptying the weapon at the audience. Fortunately, it was a blank and no one was close enough to be injured. The point being, you never know what sort of crazy is going to come out of your audience.
Larry Becker has a clever method for Russian Roulette, but, as I understand from mutual friends, he's almost been injured a couple of times when he lost focus.
Bob Cassidy, who also did a strong version of Russian Roulette also lost focus one evening. Fortunately, he had a secondary method that he could fall back on that saved him.
As I mentioned previously, Fogel lost focus and was shot at least twice with his own rifles.
Part of the problem of having your own marksman is that they are always trained to hit the target. It is extremely difficult to vary one's ingrained training to deliberately miss a target. A second's lapse in focus and it's all over.
Then again, if you REALLY want to make headlines, do the genuine article. I believe there was a performer in Germany who had a metal box that he put in his mouth and had a rifle bullet shot at him. He "caught" the bullet in the metal box. Everything was very precise and there was no trick. He made certain that the load in the cartridge was low enough and he made certain he aligned his mouth perfectly with the trajectory of the bullet. I suppose that could be done today with a laser sight, but if you do it enough times, something unforseen will happen because in this sort of thing you can't compensate for every circumstance because you cannot imagine every possible situation.
There are lots of other effects in magic that are more entertaining and far less dangerous.