Take a look at your house bolt. You will see the main part of the bolt and then you will see a separate (on most house locks) mechanism that is small and round (a plunger if you will). Well this part is not supposed to drop into the hole on the frame of the door. Unfortunately most installers are clueless and many times it does. When it does this if someone can get access to the bolt they just slide it in using either something with a sharp tip or even a credit card. The purpose of the small plunger is to keep the bolt from being retracted back into the door when someone tries to jimmy the bolt. It's AMAZING how many doors aren't installed properly. Even on high security locks this is the case. We had 4 high security locks installed at my last job and were approved for classified storage when I decided to check the locks. I could bypass all of them them in less than 2 seconds.
I would suggest that EVERYONE check their high security locks for this installation error.
Even this lock is prone to this problem.
Unican-Simplex-Push-Button-LSS-_i_LBM63534Z.jpg
To see how this works open your door and push in on the small plunger and you will notice that your bolt/latch can not be retracted into the door. Now let the plunger come back out and then press on the bolt/latch and it will retract into the door. The plunger should rest against the strike plate when installed and not go into the hole the bolt goes into for this reason.
Hope this helps.
