I remember good ol Morpheous' servers ( bless his lil soul) where spawn attacking would result in instant death.
the mod you are referring to is a Mattie event script known as the Anti Spawn killing script , unfortunately i couldn't find the download section on there forum But to be honest i didn't spend that much time looking , ill edit this post when i find it. for the time been i did manage to find a forum for it which can be found here- http://forums.mattie.info/cs/forums/...highlight=anti

i feel that this will be the best bet in tackling the spawning killing issues as although restricting the riffles has caused a dramatically decline in the amount of cases , its still possibles to spawn kill with the standard weapons as demonstrated by VeNom.