Hmm, yes, I'll try that, hopefully if this works my "Behead the Undead" project may become a reality, here's what it's based on:
http://www.youtube.com/watch?v=HBzM1nMg4PI
(this guy sucks, he's not using the crosshair! I got just above a million points on this challenge then I got fed up

)
Edit: It works!!!!!! and no messy ACS either!
actor TestZombie
{
spawnid 4
obituary "%o was killed by a zombieman."
health 500
radius 20
height 48
mass 100
speed 1
painchance 200
seesound "grunt/sight"
attacksound "grunt/attack"
painsound "grunt/pain"
deathsound "grunt/death"
activesound "grunt/active"
dropitem "Clip" 256
damagefactor "HeadShot", 100
MONSTER
+FLOORCLIP
states
{
Spawn:
POSS A 1 A_Look
POSS A 0 A_SpawnItemEx ("HeadTarget", 0, 0, 48, 0, 0, 0, 0, 16)
loop
See:
POSS A 1 A_Chase
POSS A 0 A_SpawnItemEx ("HeadTarget", 0, 0, 48, 0, 0, 0, 0, 16)
loop
Death:
POSS H 5
POSS I 5 A_Scream
POSS J 5 A_NoBlocking
POSS K 5
POSS L -1
stop
}
}
Actor HeadTarget
{
radius 8
health 1
height 8
painchance 255
mass 1000000
alpha 1
bloodcolor green
DamageType HeadShot
+SHOOTABLE
+NOGRAVITY
+NOTELEPORT
+NODAMAGETHRUST
states
{
Spawn:
TNT1 A 10
stop
Pain:
Death:
TNT1 A 1 A_Explode(500,2,0)
stop
}
}
Actor NewDoomPlayer : DoomPlayer replaces Doomplayer
{
damagefactor "HeadShot", 0
}