I have a S&W 1911 that the slide is dropping when I insert a new loaded mag in and bump the bottom of the mag. It doesn't fail to lock back on last round in a mag though.
The one I had never did that, but if it did, I would look at the slide stop. See if you can't duckduckgo yourself a picture of a new one. You're still good as is though, you just have a new feature.
Have you tried different magazines?
Have you tried different magazines?
My first thought as well.
Disturbance from inserting a loaded magazine is jarring the slide stop out of engagement. Check the slide stop and notch for insufficient depth of engagement and/or rounded corners.
If the slide stop has a rounded corner, it’s likely too soft and should be replaced rather than filed square. Hard, tall, aftermarket slide stops (such as Ed Brown’s) are available from Brownells.
A rounded slide stop notch corner will often show displaced metal which can be carefully peened back into place using a brass drift punch, but is an indication of insufficient slide hardening and/or an overly strong recoil spring.
If you can thumb-push the slide stop into full, solid engagement with the notch, then the magazine follower contact with the slide stop is likely insufficient. You must then determine whether the problem lies with the stop or the magazine.
The foregoing is but my opinion. You must keep in mind that opinions are like A-holes. Everybody has one and most of them stink.
Update;
I tried to repeat the problem e few minutes ago and could not. Tried with the same mags that the problem happened with. It functioned normal. It happened yesterday on the last 2 mags that I loaded. Maybe some "dirt" caused it and then fell out. The notch in slide and shoulder of slide stop look like a good square fit.
Anyhoo I appreciate the help with it.
Who cares consider it a speed reload?
I had a G19 that would do that - always thought of it as a feature.
"Maybe some "dirt" caused it and then fell out. The notch in slide and shoulder of slide stop look like a good square fit."
No, it wasn't dirt. It was us thinking about it.