Shield Plus slide not locking back

[shootsacanon]

I have about 250 rds through my Shield Plus without any issues.

I've been carrying 13+1 with the extended mags for the last two months or so, and today emptied that mag for some dry fire practice.

To my surprise the slide is not locking back on the 13 rd empty mag. If I manually push up on the mag, to flush that 1mm gap between the grip and the baseplate, then it will lock back.

The 10 round mag is locking back on empty as would be expected, but I've only had it loaded to capacity for 2-3 weeks.

Anyone else experienced this with the new Plus mags loaded to capacity for an extended amount of time?

 

[newpewpew]

I did notice that if the gun got a little dirty, the slide lock might not lift up as high with an empty mag. Could try cleaning the area where the slide lock contacts the slide or frame, to see if it makes any difference?

Does the follower on an empty flush mag rise up higher than the follower on an empty extended mag? If so, maybe the spring in the extended mag isn't pushing the follower high enough.

I also lost the locking open on empty function, after I messed with the spring in my 13-mag. I cut off a loop thinking it would help with racking with all 13 rounds loaded, or the problem with the 13th round getting dented by something above it. Cutting the spring didn't help.

I got the lock open function back by bending the slide lock spring to lower its stiffness. In the picture, I angled the #2 part upward just a tiny bit, and if the slide lock had free play, I bent the #3 part down just enough. Not recommending making own alterations without accepting the risk, though.

 

[Walnut777]

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I haven't shot my shield plus yet. I did take out my m&p 9 compact 4 inch today. I mistakenly bought a new in the box gun that's discontinued. I was looking for the 4.25 inch.
Anyways I couldn't get the slide to lock at all unless I shot one handed.
Which leads me to believe when I got home it has to be something with the way I grip with my thumbs down the frame. Will see next time I go target shooting

 

[Walnut777]

Admin if you get a notification I said a cuss word. I apologize. When I posted I notice the word "shot" looked like this: ****. My autocorrect changed shot to a different word. My phone knows me too well.