Did you register your account as being under 18 years of age? If so, then you cannot get blood. If you DID make it older than 18, then check out the settings... should be down the bottom of the list somewhere.
THERE IS STILL A WAY PUT HOW TO HAVE BLOOD IN CA in yahoo answers and it shows a way to enable it even if u registered under 18 yr old
The way to get blood is go to C:\Nexon\Combat Arms\Profiles and then open Player.txt And CTRL+F and type in Gore Change the 0 to 1.