From
http://www.firearmstalk.com/forums/f14/alloys-metals-used-gun-manufacture-36032/"The first guns were likely made of brass and bronze. Later they were made of wrought iron, then steel/iron combined as Damascus or Twist , then various steels. Steels are in themselves a whole field of study- it forms different crystals at different temperatures- research terms cementite and austentite. There are dozens, if not hundreds, of different alloys (you DO realize that steel itself is an alloy?) that have different amounts of manganese, chrome, nickel,carbon, vanadium, molybdenum etc. Then you move to the field of stainless steels. There have been gun barrels made that were a combination of steel, aluminum, and synthetic fibers. There are "airweight" framed guns made of aluminum alloys (and THOSE are a field of its own), and titanium, Scandium alloys, etc.
Various polymer framed guns are forms of plastic, combined with steel- have even seen one AR style frame made of PET (same stuff plastic soda bottles are made of) and ONE made of wood. M60 machine guns have barrels lined with Stellite, and some guns have firing pins made of berylium alloy. I have even seen one handgun made for a spy agency that was ALL plastic."
Here is a closeup of the Gruffs with the gun (the illustration from the DFRPG book):
http://www.jimbutcheronline.com/bb/index.php/topic,15682.0.htmlAnd in that thread, someone brought up the iron issue, to which iago replied "That's assuming the gun's made of iron or an iron alloy like steel, of course"
http://www.jimbutcheronline.com/bb/index.php/topic,15682.msg723267.html#msg723267Soooooo... I guess it isn't iron or steel?