21', or seven yards. Most people I know, no matter how "fast" they run can clear at least a yard in a single stride. I am relatively short, and can clear over 2 yards in one stride running. That's less than four strides for me to get to someone, and would take only a matter of 1-3 seconds. At seven yards, it would be best to try and run from a knife wielding attacker, or try an evasion/kick combo. The range for a gun to become "yours" is your armlength plus his armlength or within. Remember that most people can move faster than you can "see", so I could have stepped out of the line of fire parried/grabbed the gunholding arm before the wielder can process that I've done it. I have actually pressure tested that one, and was honestly convinced that I was looking down the barrel of a .22 handgun and not a pellet gun. The other guy never even got a shot off. I still don't make any more claims about being "bulletproof" though. I don't want to actually prove it facing down the barrel of a real gun next time.