The Collaborative International Dictionary of English v.0.48:

Gunflint \Gun"flint`\, n.
   A sharpened flint for the lock of a gun, to ignite the
   charge. It was in common use before the introduction of
   percussion caps.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gunflint
    n 1: the piece of flint that provides the igniting spark in a
         flintlock weapon