Ghost Guns

Before you call BS on the strength of nodular iron, you might want to check out ASTM A897.

ASTM A897 is not a chemistry spec, it is a set of mechanical properties that can be wrung out of common nodular iron (like crankshafts and steering knuckles) via heat treatment.

Basically, heat to 1800 F and hold for an hour.  Dump into 700 degree molten salt bath (50% potassium nitrate and 50% sodium nitrite works) and hold for 20 minutes.  Then air cool.