Slide is supposed to lock without having to depress the slide lock correct? You only depress the slide lock to release? Sorry dumb question.

with an empty mag yes

I think it should lock open only when there's an empty magazine in the gun. No magazine and it won't lock open on its own.

This

yes, when the mag is in and empty it should lock open.

If the gun is failing to lock open after the last round, watch your grip and make sure you aren't holding the slide catch down with a finger (seen this with a M&P 9c).

If that isn't the case, then the ammo could be weak and not have enough power to get the slide all the way back where it can lock open or the mag spring is weak.

That's what I thought. Thanks THF. And Smiths know off hand what that repair job costs? I have an angle I an Older 9mm but it needs that work and new sights.

if its just a mag spring or recoil spring, you can do that yourself.

What needs to be repaired?

I would thing the mag spring is the issue or build up not letting the follower ride to the top?

if your grip is good,
try different ammo first

if still persists, replace the mag spring and recoil spring and should be good to go

try a different mag, mine was doing the same thing, mag springs

First try a different magazine

The slide stop is a replaceable part

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