Howdy
If it is a "C" prefix then the gun by all rights should be a Carbon steel gun. Most likely a nickel or hard chrome. Many guns have been sold as SS that were actually a nickel or hard chrome. The other possibilty is that the gun was a lunch box special put together and sold by an employee. Really hard to say without looking at it. But the serial number would indicate that it was a carbon steel gun.
Hope this helps....
L8r
Conley Janssen
USMC87-93