There is a huge misconception running around "Especially on Gun Forums" that the Tueller Drill somehow establishes a hard and fast distance Rule that applies when one is about to face a knife/club threat . While one is never justified in shooting a person at extended ranges of 10-20+ yards when armed with a knife or club it is never to early to prepare to deal with an obvious threat . The range you begin to start the draw is dictated by various factors like how you are carrying your weapon to if your hands are full with something and include the speed at which the threat is advancing on you . If you're exiting a store after a shopping trip and are in the process of strapping your infant child into his car seat and someone yells a threat at you from 50 yards and begins advancing at a quick walk the time to give the threat your utmost attention and begin reaching for your gun is NOW not when he reaches the 21 foot mark of you . If you are carrying in an ankle holster or a purse and you wait till he is 21 feet away odds are you're dead . If one has done much reading on the drill you will quickly see that if one takes it as a "Rule" they are making a huge mistake because a quickly approaching threat will be right on top of you by the time you fire the first shot if you start with a holstered weapon . All of this also only supposes a single attacker if you find yourself facing two or more attackers even if only wielding clubs or bats the distance at which you need to engage becomes greater . Tueller is a reaction time drill/demonstration NOT A RULE and it most certainly doesn't apply to a firearm threat .