Return of Zombie Ops is a zombie modification for Call of Duty 4, it features content from Black Ops Zombie mode aswell as from Modern Warfare 3 Survival mode and Ghosts Extinction mode. It's set slightly in the future with some weapons from Ghosts, Black Ops series and Modern Warfare series.
Details:
FN P90
FN 8.7x28 mm Full Auto
Silencer is an option
Does it replace the old one, or it will be NEW gun?
Yea, it replaces the COD4 one. Having a gun twice isn't really a viable option when you're very limited on guns.
So you're saying, that there is limit on weapons in CoD4 MW?