I’ve heard varying distances on this one, the most common is 2 meters, 8-10 feet which came from Michael Janich when he was discussing using a gun for self-defense. The short answer is: no, it’s not a myth. The length varies, but it is true.
Guns are ranged weapons.
They are very powerful weapons and they are terrifying, but they do not confer automatic victory. If you can’t get the gun out in time, then the gun is worthless and someone can reach you before that happens then it’s over. It does take time to draw, sight, and shoot. Training for precision shooting in close quarters will negate it some and should be necessary for anyone looking to use a gun for self-defense, but one of the major concerns for the self-defense community (particularly when advocating for guns) is that the hand to hand component is neglected along with teaching how to defend and create the time necessary to reach the gun.
Training tends to create a mindset where the student automatically reaches for the gun, but in cases like a mugging or where the altercation happens in very close ranges then that mentality can get a person killed. The aggressor is on them before they have time to pull the gun, the action of reaching for it opens up vulnerable parts of their body, and they get stabbed.
If the weapon is not in your hand or you don’t have time to draw it, then it’s useless. This is true of all weapons, they all come with situational weaknesses. Whether it’s the pepper spray that ended up at the bottom of your purse or the rifle caught on the doorframe or the handgun still in its holster, it doesn’t really matter.
Assuming any person will automatically win because of their weapon is fooling themselves and guns are no different. They’re tools, very dangerous tools, and must be respected for the damage and misery they cause when used inappropriately (or even appropriately) but it’s up to their user to keep them in a position where they keep their advantage.
This is why the answer to every versus question is: probably with a side of “if”. Everything about combat is conditional to the people involved, the situation, and what actually happens. You prepare as best you can, but you can’t prepare for everything and it’s never really very simple.
All combat rules can be subverted. Every weapon advantage can be turned to a disadvantage depending on change of situation and scenery.
The problem that comes in with a lot of writers is the assumption that they give Character X a weapon then they are only conferring X skill set. Which, no.
The person with the knife within the 8 foot range will only win in the bullrush/stab if the person with the gun automatically reaches for their weapon. If they instead choose to go into hand to hand, manage to deflect the knife or draw a knife of their own that they are carrying (and many military types do), then the situation changes. They fight them in hand to hand, create an opening with which they can draw their gun, disengage, get to distance, and then they shoot.
Combatants do not train on just one weapon.
People are limited by what they’ve learned and what kinds of combat they’ve been taught or the situations their prepared for. If the self-defense courses you take only prepare you for the mugger who leaps out of the bushes, then you won’t be ready for the one who politely asks for the time or the uncle/father/brother/sister/mother/cousin/trustworthy friend of the family who takes your wrist. Train only in point shooting for self-defense, then you’re at a loss when they’re already inside hand to hand range.
The key thing here to remember is: people and people are what is usually forgotten when constructing scenarios. A person who wants to hurt you is going to assess the situation and make decisions based on what’s best for them or will lead to the most likely outcome for success.
If you see a person carrying a gun and you only have a knife, you have two choices. You can either walk away (then, the gun has done what it has supposed to and acted as a deterrent) or you can try to figure out how to negate the gun from the scenario.
You (and your characters) need to look at a situation and ask: how can I win?
This is why many characters in fiction end up acting in ways that are unrealistic or make no sense because they’re behaving on either assumed statistical differences or the author is looking at the situation from the outside in. Look at it from the inside out. If one plan doesn’t work, then come up with another one.
You can’t take the gun in a head to head if it’s already in their hands and if you can’t reach them, but if they haven’t realized what’s coming yet? Oh yes.
Mindset. Planning. Psychology.
Weigh the consequences of failure versus victory. Is it worth it? Is it not? What do you need to do? The aggressor usually has the advantage over the defender. They have the initiative, the advantage of surprise, and they’ve already made the decision and committed to their course of action. The defender has to play catch up. This is the major reason why good self-defense programs focus on identifying threats and teaching its students how to look unappealing as victims while avoiding common traps. A situation that ends before it begins is a victory all by itself.