With no magazine in or any ammo, rack the slide. It should propel forward.
With weapon pointed in safe direction, squeeze the trigger. It should "snap" with no rattle.
Insert an empty mag and rack the slide. It should lock and not propel forward.
Press the thumb catch. Slide should propel forward.
Drop magazine, With weapon pointed in safe direction, squeeze trigger. It should snap again.
Congrats! You've performed a function check on your Glock, meaning you put it together properly.
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