I took my brand new glock 23 to the range for the first time and had a problem with the side locking open several times while firing with rounds still left in the mag. Sometimes it would happen as much as three times in a row. It was not due to a jammed round as I was able to release the slide by pushing down on the slide release which then chambered the next round in the mag. I took it home, cleaned and lubricated it, then took it back and had the same problem. Before I fired it for the first time I had replaced the slide lock and mag release with extended ones as I have done on my other glocks. Does anyone have any suggestions as to what might be the problem?