How do you check the firing pin? In the manual it says to "pull the firing pin lug all the way back to the rear of the slide"....."and don't let it slam back" Only when I try this, the firing pin just clicks/snaps once inside the breach face and stops. Doesnt even get close to the rear of the slide. Is this normal? I'm new to Glock so if it's a stupid question...sorry. Just want to make sure nothings effed up.