I’ve had this happen on my PPQ M1 a couple of times over probably 10,000 rounds. Every time the gun has fired. Looking at the slide locking process, the first thing you realize is that the only thing holding the slide back is the lever on the side of the slide. This is often referred to as the “Slide Release” lever. It is more properly named the “Slide Stop” as that is it’s primary function and the only thing locking the slide back.
Follow the the cycle. The last round is stripped from the magazine, as the bullet clears the magazine the magazine spring forces the magazine follower up to the top of the magazine. On the side of the magazine you will see a cut out where a little tab on the follower moves up and down. This little tab pushes up on the slide stop allowing it to engage a notch in the slide, holding the slide back. When you insert a loaded magazine the follower is force to the bottom of the magazine and is no longer pushing up the slide stop to engage the notch in the slide. You can watch this happen by removing the slide and inserting an empty magazine. Note the position of the slide stop, push down on the follower with your finger and note the position of the slide stop. A small spring hold the slide stop in the down position until the empty magazine follower forces it up into the lock position. From this you should have an idea of the areas to look at. First the magazine: weak or dirty magazine spring or follower, worn tab on the follower causing it to not engage properly. The slide stop: worn tab on the slide stop, slide stop spring dirty or in need of lub.
All of these could contribute to a premature slide release if the magazine is slammed too hard, jarring the slide stop lever out of position. Remember once you remove the empty magazine there is nothing holding the slide in the rear position but friction between the lever and the slide.
To OldFart’s point, trigger does not reset until about the last 1/8” of forward travel, before that you will have no trigger engagement, therefore no click. You can test this using a empty gun. Pull the trigger until it is released, then slowly pull back the slide until you hear an audible click as the trigger resets. Prior to that last 1/8” you will have no trigger at all. I suppose you could have a weak or dirty firing striker spring that doesn’t allow the striker to come forward. This needs to correct this condition immediately as it can be extremely unsafe.
