The Assault Rifle is a cut weapon from Zombie Master, it had the same sounds from Counter Strike, it was to be the only Assault Rifle from Zombie Master, altrough it is very difficult to find ammo for it.
The Assault Rifle has a useless M203 grenade launcher on its underbarrel
Some body models have an Assault Rifle on them, but cannot be picked up.
The Assault Rifle is actually a M4A1 with Grenade Launcher.
Some admins in custom servers can equip the Assault Rifle with them.
If the player install mods or hacks on ZM, he can use the AR