gunlock

/ˈɡʌnˌlɑk/
noun
  1. The mechanism of a firearm that ignites the propellant charge, typically including the firing pin, hammer, and trigger assembly.
    • He replaced the old gunlock with a modern, more reliable one.
    • The gunsmith carefully inspected the gunlock for any signs of wear.
    • A faulty gunlock can cause a firearm to misfire.