Man,.........If someone here thinks he is going to shoot a BG with a cock weapon, finger on the trigger, and pointed at someones head, you have been smokeing something. I'm am not trying to be a smart@$$, but in that scenario you would have to make a "Nonreflex Brain Stem" shot. Anything else and he can still pull the trigger and maybe even kill more than one. That is a difficult enough task to do with a sniper rifle, let alone an offduty / undercover handgun. I don't know of anyone who makes a holster for a Rem 700 pss. I guarantee you would be prosecuted for causing the death of the victim, either in court or in the media.
The only way I would ever attempt it is if I am standing right behind the guy and can make a contact shot to the back of the head.
"Fast is Fine but accuracy is final.".....Wyatt Earp.