Question about exterior door locks

[GearUp]

I just installed a new doorlock on my front door today and I always had this question in mind.

On the latch itself (half moon piece I guess you could say) there is the main piece, and the straight little bar that is on the back of it that goes inside with the latch when you turn the knob, but is on a separate spring. (You can push that piece inside, but not the half moon piece, or you can push both in at the same time.)

Is this just for spacing or something else? The half moon piece latches, but not the little bar I'm talking about. I marked it with a magic marker to see, and it stays outside of the strike plate hole.

Thanks all.

[jnaas2]

That little piece that you are talking about is suppose to stay outside. If you open the door and just push the little piece in you will see that the latch is locked in place and cant be pushed in. If both pieces are out they will both go in at the same time. The reason for this is with the door shut the strike plate lets the latch go into it to keep the door shut and pushes the little piece in to lock the latch and keep it from being opened with a knife, or as you may have seen on tv a credit cark. And when the door is closed, both go in at the same time to allow the door to be closed