Shooting Iron Meaning

(chiefly US, idiomatic, dated) A firearm, especially a handgun.

Example: 1895, G. A. Henty, In the Heart Of The Rockies, ch. 15:
  "It ain't the rifle, Harry," Sam said good-temperedly; "it is the eye that is wrong, not the shooting-iron."
1900, Joseph Conrad, Lord Jim, ch. 25:
  Look like a fool walking about with an empty shooting-iron in my hand.
1943 June 14, Cheap Firepower:June,
  The U.S. Army's newest war tool, the M-3 submachine gun, unveiled last week. . . . a stark, crude, unlovely shooting iron.