Greeting's All-
Kim, Colt produced three different firearms on their famed D-frame. These
were: the Detective Special with a weight of 21 ozs, the Cobra (your gun)
with a weight of 15 ozs, and finally an Agent with a weight of 14 ozs. All
were very popular off duty weapons, in law enforcement circles. Colt also
made several minor changes along the way; hence the different series of
each firearm. For instance, I collect Colt D-frame Detective Specials from
the 2nd series, which ran from 1947-1972; cuz 1947 was my birth year.
Also, to the naked eye the Agent will be noticeably different; as the frame
is shorter in the grip. To my knowledge, the Agent was only manufactuered
using an anodized bluing process; while the DS and the Cobra were also
offered with a nickel finish.