Well, I've decided that I'm a jynx when it comes to nail guns.
It almost happened again, and had I not been holding my fingers deliberately out of the path of any misfired projectiles I would have been in serious pain.
Then, a few minutes later, one of the shop supervisors (a faculty member) was helping out because somehow the 2x4 that was being used for a piece of framework got twisted like a spiral. He put a guard piece in between the nail gun and his body, and sure enough the damn nail gun double-fired again--launching a nail directly into the guard that had been put in place. Had the guard not been there, the poor man would have had a three-inch nail lodged in his genitals.
*sigh* fucking Mondays.