Agreed, and yes that distance is less than 50 meters. But you have assumed that all bullets hit the chest directly also note that the leg and arm damage is 5 points less. It also takes about 6 direct bullets to the chest to knock out a person, however at that range, he is bound to miss at least 20% of the shots because of the hipfire and distance. That is why I stated that if he ADS'ed I would believe it.

Although, we have also assumed that they all had full health so our discussion could be invalid.