I guess it depends to me. If you wanted to be very realistic, then I would say it depends.
A upper chest /head shot should kill anyone, no matter the sniper rilfle, in one shot.
What I really liked about COD:UO and the Extreme mod, was that you bled out if you were wounded bad enough.
For example, I would like to see if you snipe someone in the chest, and it doesn't kill them, (only drops them to 2 bars) then if they don't find health in 10 seconds, they lose another bar, and an additional 10, they die, and you get the points for them. I shot a guy in the neck last night with the Barrett from about 30 feet. We were both prone. Guess what, he turned and got me with the g36E. He should have been a headless horseman, but I still got killed. That faction really bothers me.
But I also don't think if you snipe someone in the feet, it should drop them to 2 bars either.
I would rather see the whole sniper damage model reworked, and something like, if you shot the victim in the feet, it would drop them - 1/3, upper legs and stomach - 2/3. Upper chest and head - kill shot.
Thats how I would fix it.