Excerpt from this Guide:
THE GLOCK “SAFE-ACTION” PISTOL
The following is a description of how
the GLOCK “Safe-Action” trigger mechanism functions.
CAUTION: It is
possible that a loaded round may still remain in the chamber when a
loaded or empty magazine is being removed or inserted. Like most
firearms, any round in the chamber will discharge by pulling the trigger
with the Glock magazine inserted OR removed from the
firearm.
Remove the magazine, cock the pistol,
and CONFIRM with your eyes and finger that the chamber
is empty and that there are no rounds present. The GLOCK pistol is
actually considered half-cocked at this point. The firing pin has been
slightly tensioned, the trigger is moved to its forward position, and
the trigger safety protrudes from the trigger.
When you first pull the trigger back
about 1/4 of an inch, the trigger bar slides behind the trigger ramp,
the firing pin moves up, and the firing pin is tensioned. The Glock
pistol is now on “FIRE / SAFETY OFF”.
When the Glock trigger is pulled back
further, the trigger bar releases the connector which releases the
firing pin and discharges the loaded ammo.
The recoil produced by the fired round
forces the slide backwards.
At about the .012 position, the barrel
is released from the slide and moves down over the locking block.
The Glock slide continues to move
backward and the spent cartridge case is pulled out of the chamber by
the extractor and tossed out towards the right by an ejector.
A ramp in the slide moves the
connector and separates it from the trigger bar and lifts it off the
trigger spring and toward the path of the firing pin face.
Next, the recoil spring forces the
slide forward and the trigger bar slides on to the safety ramp near the
firing pin - the firing pin safety returns back to its original position
- a slight tension is placed on the firing pin - if present, the next
round is stripped from the magazine and placed in the chamber - the
barrel is locked into slide and the pistol is ready to fire.
Once the last round has been fired,
slide will be held back in the open position by the slide stop level.