I picked up my new gun today: Glock 23 After going through the Safe Handling Demonstration, the salesman gave me some tips and advice. One of the things he said is that there are two ways of releasing the slide after it has been locked back. 1) Pushing down on the slide lock, enabling the slide to go forward 2) Manually pulling the slide back and letting it go forward. He informed me that either way is fine, but if the gun is empty...never to use the first method (pushing down on the slide lock to let the slide go forward) he said if the gun is empty then it could get damaged by doing that. he told me why, but he was going into technical terms and I'm a newbie to guns so I didn't know what he meant. Anyways, is this true?