Wrong.
West units :
myunit Fire ["M203Muzzle","GrenadeLauncher", "GrenadeLauncher"]
East units :
myunit fire ["GrenadesMuzzle","GrenadeLauncher","GrenadeLauncher"]
Make a whole group of grenadiers fire their nades :
1- initialise your group
grengroup = group this
2- fire command for the group
EAST
{_x fire ["GrenadesMuzzle","GrenadeLauncher","GrenadeLauncher"]} foreach units grengroup
WEST
{_x fire Fire ["M203Muzzle","GrenadeLauncher", "GrenadeLauncher"]}foreach units grengroup