Sounds like a wimpy spring or debris in the slide release such that it has occasional random operation. Thoroughly clean and lube the slide release such that it moves easily and fully into the notch in the slide.I am starting to have this problem. The slide sometimes does not lock back after the last shot and when I slap the mag in with the slide back it closes without hitting the release. Any suggestions before I send it in?
Be sure the slide can move freely all the way back, everytime, to allow the slide release to lock. In that split second the slide is back the slide release needs to pop up into place. Observe the operation with an empty mag inserted.
The follower in the mag MUST move freely, especially on the last round. The mag spring must have enough tension to push the follower up against the slide release such that it locks the slide open in the milliseconds the slide is back. Remove the mag spring and possibly stretch it out a little bit and lightly lube the 4 sides of the follower. Without the spring installed, work the follower thru the magazine and observe if there is any binding in the end of travel-mag empty position.
My 2 cents.
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