(as) sure as a gun

(as) sure as a gun

obsolete With utmost certainty; quite definitely. (That is, as sure as a gun is to fire when its trigger is pressed. This idiom has largely been replaced with the phrase "sure as shooting.") Lord Henry, sure as a gun it was those two miscreants who have made off with your prized heifer. Come into a great fortune and, as sure as a gun, the number of those who would be your friend increases tenfold.
See also: gun, sure
Farlex Dictionary of Idioms.
See also:
  • (as) sure as shooting
  • dimber damber upright man
  • Londoner
  • be a (something) through and through
  • beef to (the) heel
  • beef to the hoof
  • hoof
  • (one's) all
  • all
  • give something your best shot