[Rocklobster]

Without looking at the gun,it sounds like a spring-and-plunger assy. problem to me.

 

[Bob Brown]

I suspect it's the top, rounded part of the slide stop lug...the part that goes inside the frame and gets pushed up by the mag follower to lock into the notch in the slide.
If that rounded part is worn, or has been "fixed" by someone not familiar with the way it's supposed to work, it can have too much gap and instead of holding the slide stop in, can let it move to the left enough to cause the mag follower to miss the lug entirely. AND, it will move enough to lock the slide back, usually at a point between the lock-back notch and the takedown notch. Best remedy is a new slide stop.

 

[feedramp]

This came up on the forum some weeks ago, and the solution was unusual, if not unique.

If the suggestions offered thus far don't work, you may want to see if any part of your hand (or either hand, if you shoot two-handed) is pressing against the rounded end of the stop, and thus trying to push it out. There will be a brief moment during each cycle where the slide will be in the right position for the stop to move to the left, and thus come partially out of the frame. If the pressure against the end of the stop is high enough, it will come out a little bit.

Interesting.

 

[Bob Brown]

Hey feedramp. I didn't catch this on the thread before and didn't think of it 'till I read your post. And you're absolutely right.
Over the last few years I've had a few guys come over with this problem and it'll drive you nuts until you find out they're doing some experimenting with their two-hand grip.
If this is his problem, the fix is really easy.

 

[Mistral404]

Thanks for all the info.
The insight into the grip was quite good. Unfortunately, I wish that was the problem. But my fingers are well clear and not causing the problem.

An interesting note: I call Dawson Precision on Friday afternoon at 5:30 Texas time. The were the nicest group of people. Dave got on the phone with me, he was will to walk me through the measurements needed to assess the problem and possible solution right then. I was pretty impressed with his willingness to chat with someone who never even purchase a gun from him.

Anyway to make a long story short, it may be the slide stop itself. I have replaced it and will test fire the gun tomorrow.

I will examine it for the other suggestions also.

Again, thanks for all the replies.