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During a recent conversation, the topic of personal defensive space came up. Invariably, the subject on this includes what many call the “21-foot rule,” or, more properly, “The Tueller Drill.” It was developed in 1983 by Lt. John Tueller while he was a firearms instructor with the Salt Lake City police department. The idea behind the drill is to identify if an officer could draw and accurately fire upon an aggressor armed with an edged or striking weapon before making contact with the assailant. I first heard of the “21-foot rule” while attending my concealed-carry class almost 10 years ago. I don’t remember if the instructor gave credit to Lt. Tueller or even explained in detail how to bring the odds back into my favor. 

To give some perspective on how close 21 feet is, it is the length of an average longbed pickup truck. For an assailant to get from the front to the back—where you might be—it will take them around a second and a half to cover that distance.

Natural Reactions

 In that time, your body is doing several things. The first is your brain is trying to assess the threat. This might take up to half a second. Next is your response, another half to full second.

Most good shooters I know can draw and get the first shot off in just under one and a half seconds. However, these are not average shooters. They practice these types of scenarios often and continue to change them to get better. Most handgun owners are not in this category … but should be. You know the ones—once a month at the range (maybe). Some are even less experienced—those who get their concealed permit, get their gun and holster, and then never train.

Don’t be that guy or gal!

Get off the “X”

There are a couple things you can do to train for this type of incident. Most importantly, get off the “X.” Don’t be a stationary target.

A person running at you is building momentum; so, by moving laterally, you do two things. You increase the distance between you and the assailant, and you cause the assailant to change direction, which can throw them off balance. This gives you more time to draw your own weapon. Your movement needs to be quick and more than just a step or two out of the way. If possible, move to the opposite side that your attacker is armed on. This makes it harder to swing the weapon at you if they go past you. Try this by having your training partner run at you and then move left or right. See what this does to the “attacker.”

You can also change levels. Start by moving laterally; then, go to the ground, laying on your back as you draw your weapon. You can use your feet and legs to deflect both an armed and unarmed attacker. You are less likely to suffer an injury that will prevent you defending yourself further.

Test Your Response

The NRA offers a course for personal protection in the home (PPITH). A drill is demonstrated to emphasize the “21-foot rule.” In the drill, the defender starts with gun in holster and facing downrange. The “assailant” starts with a hand on the shooter’s non-firing shoulder. At “go,” the attacker begins running in the opposite direction of downrange. The shooter draws and fires at a target fewer than 21 feet away. On the sound of the shot, the attacker drops an object so that it can be measured from the “start” position. This gives the shooter an idea about what their real safe distance is. Based on updated data, 30 feet is a more realistic distance.

“…by moving laterally, you do two things. You increase the distance between you and the assailant, and you cause the assailant to change direction, which can throw them off balance. This gives you more time to draw your own weapon.”

POSITION 1 is your best opportunity to get a good grip and make solid contact with the firearm.

In POSITION 2, the firearm is drawn from the holster and is immediately pointed in the direction of the threat in the event the threat advances toward you.

POSITION 3 is the meeting of the dominant hand with the non-firing hand for stability and better aim. The gun remains trained on the threat.

POSITION 4 at full presentation. This is your best—and most stable—position for aiming at the threat.


A host of things can change the outcome. Experience will likely be number one. Other variables, such as fitness level, type of holster and carry mode, light conditions, what type of weapon the attacker is carrying (baseball bat versus knife) and perhaps the age of the shooter. You should also make use of any obstacles available (shopping cart, vehicles, bushes).

My additional suggestion is that you do not need to come all the way to position 4 to take your first shot; you might need to be able to take your first shot from position 2 (see the “Shooting Positions” sidebar on page XXX). This is something you should practice … under qualified supervision. In reality, the “21-foot rule” is not a rule at all; rather, it is a guideline about where you should set your training. By practicing via the NRA’s PPITH drill, you can safely get an idea about where your safe distance is.

This is also an exercise you can practice while dry-firing. However, make sure you have removed all live ammunition before practicing this drill. Of course, this advice is for blunt and sharp-edged weapons. If the attacker has a firearm, the tactics are very different.

It is also important to remember that you will not become an expert simply because you read it here. You need to train and train hard. Expertise comes from practice and from seeking qualified training from a good instructor. Hands-on training with constructive criticism is what will prepare you to defend yourself, should the need ever arise.

When your stress level is up, and your adrenaline is flowing, you will revert to instinct and ingrained training—not something you saw once on YouTube or read in a magazine.


POSITION 1: The firing hand moves to form its grip on the pistol grip. It is important in this first step to get a good grip on the firearm; it is unlikely you will have time to adjust in a defensive situation.

POSITION 2: Once the pistol is clear from the holster, it is instantly pointed toward the threat while continuing to move to the center of your body, connecting with your non-firing hand. (As a note, a slight cant away from your body with a semiauto will prevent the slide from contacting you if fired from this position.)

POSITION 3: Your non-firing hand solidifies the two-handed grip, with the muzzle pointed at your threat. In position 3, your finger remains off the trigger—except if the threat raises to the point that you must immediately shoot. It is recommended you only shoot from this position if you are proficient or possibly using a laser sighting system. Remain aware of your surroundings and backstop. You do not want to injure innocent bystanders. This is also a good “ready” position, because it does not create muscle fatigue (unlike position 4). Again, keep your finger off the trigger until you are ready to fire.

POSITION 4: This is full-presentation position. From this position, you will be able to take your most accurate shot. This is not a position you can maintain indefinitely. Therefore, you should only execute it when you are ready to engage. Once complete, scan for additional threats and return to position 3 until help comes; alternatively, move to a more secure area to call for help.


Brian Berry is a retired Army Special Forces Command sergeant major. He is a former Special Forces weapons sergeant and has multiple combat tours under his belt. Brian is the co-founder of Spartan Defensive Concepts, at which he teaches concealed carry and defensive marksmanship courses. Brian retired in 2014 and is now a consultant currently working for the Special Operations community, as well as a senior instructor for American Survival Guide University.




Editor’s note: A version of this article first appeared in the June 2018 print issue of Gun World Magazine.