The question hence becomes, “What to do once we’ve decided to take action?” The greatest detriment you can have in a physical encounter, be it with hands, edged weapons or firearms, is the distance between yourself and the aggressor.
Unless you are behind a substantial cover your attacker cannot penetrate, close proximity is your best friend in a fight.
Mostly, this is because you have an enhanced view of the pre-assault indicators and body mechanics.
If you are close to an individual in a position that allows you to act immediately upon their body, you may have the opportunity to disrupt their ability to draw in the event the imminent attacker reaches for his weapon.
On the other side of the coin, if you were to step back to draw your firearm upon identifying a move for a gun on the attackers part, you’ll inevitably be behind the curve as you cannot react faster than they can act.
You will win this fight only if they are incompetent or you are lucky because the delay between recognize, decide and act is too great to make up.