My buddy had a borrowed RRA AR15 with backup iron sights installed on the picatinny rails on the receiver and gas block. In humans they are common residents of the throat and upper respiratorytract. This may sound selfish but I would offer support but I would try not to get into the middle of it so as I would not be at risk also. By chance we found a reference to this play, and voila, Ben found it on Amazon. Largely supplanted by the reporter gene luciferase.