Your question gave you away. No one who has had professional training would have had to ask it. All the major schools teach to not cock a DA revolver.
I am asking a question as for "what would you do?"Would you cock the hammer in an encounter or not?One person stated that the BG backed down after cocking the hammer,and that is a good answer.For me personally,no I would not cock it because of the adrenelin would probably cause me to accidentally discharge.My question isn't personal to me and the fact that people are questioning my experience for asking others what they would do is strange to me.