Any firearm, .22, .40. 9mm, .45 can kill a person, more or less instantly, if the bullet damages a vital organ.
Life and death is not like flipping a light switch, so dying instantly doesn't happen too often. Certainly a shot to the head in which the bullet damages both hemispheres will incapacitate immediately, and is eventually fatal.
$200
Maximum range of a .40 cal pistol is about 960 meters. ACCURATE range is about 50 meters.
100-400 USD
Sig Sauer P229 chambered in .40 is pretty good
DO NOT ATTEMPT TO DO THIS!!!!!!!!!!!!
10-40 usd
SAMMI publishes ammuntion standards.
It depends on which model and whether it is new or used.
Smith and Wesson
40-100 or so
About 40 USD
100-450 USD