The only scientifically proven and biologically possible way to guarantee instant incapacitation is through destruction of the central nervous system or brain. This will usually cease all motor-related and voluntary actions. If the central nervous system is not damaged or destroyed, there will be no immediate incapacitation. To allow room for error, since a central nervous system hit is very unlikely, most people use expanding ammunition. This will increase the odds of striking a part of the central nervous system, and cause faster blood loss.