I think the deer’s reaction depends on a number of factors. The first and probably most important is how pressured the deer have been. If they haven’t been pushed to you or been recently “jumped”, they are more relaxed and less on edge. If they have been driven to you, that is a different story. Any unusual sound and in my opinion, they will either turn tail and run or put themselves in high gear. Another factor to consider is how quiet the woods are that day. I have seen deer on a dead quiet day, lunge at the sound of me setting the trigger. For that reason, I cock my rifle and set the double set trigger as soon as I see them, taking my trigger finger out of the trigger guard. I only put my finger on the front trigger after I have aligned my sights on my target. If I don’t take the shot, I move the frizzen forward, carefully lower the cock, then set it to half cock and after checking my priming powder, lower the frizzen on to the pan. Then I am ready for the next encounter!