[RenSoprano]

Use the Callback:

Код:

public OnPlayerShootPlayer(shooter,target,Float:damage)

And here is a simple example:

pawn Код:

public OnPlayerShootPlayer(shooter,target,Float:damage)
{
    new Float:HP;
    GetPlayerHealth(target, HP); // Here we will take the player current health
    if(GetPlayerWeapon(shooter) == 34) SetPlayerHealth(target, HP-100); // This will kill the target from 1 shoot
    return 1;
}