Greetings everyone. New to the forum but not a noob to forums.
Just got my M&P45 from my wife as an early Christmas present. Love my wife and the gun. I started reading this forum when I began looking for my first .45. It is a great site and I hope I can contribute some good info. Here is my new 45. Planning on installing an Apex Tactical DCAEK and that's it.
In reading this forum and other places, I noticed that some people were having problems with the slide moving forward when inserting a new magazine. Some said it was normal and no problem and some said guns should not auto forward.
Couple of weeks ago I went to the range and rented a Kimber 1911 Custom II, M&P 45 and a Glock21. All were great guns. The Kimber was dead on accurate. The M&P and the Glock were very similar to each other, with obvious reasons. I chose the M&P because it fit better in my hand and shot a lot smoother. Not as smooth and accurate as the Kimber but smooth enough and accurate for a combat gun.
One thing that happened with the M&P that surprised me was the auto forward slide action. I loaded a magazine with bullets and inserted with the same amount of force as I always do with all my other guns. Not very forceful. SLAM! The slide went forward and chambered a round. It did this a few times. I thought that because it was a rental gun, and had several thousand rounds through it, the gun was just loose and worn out.
Fast forward to Black Friday when I got my gun. Came home like a happy little boy. Check the slide action and trigger. All is fine so far. Opened the slide by hand and locked it in place. Loaded a magazine with bullets, inserted the magazine with light to moderate force and SLAM!. Auto forward. Feeling a little bummed. Brand new gun and its doing the auto forward slide action.
I checked and re-checked everything. I came across a couple of things. The gun would auto forward when the magazine had one or more bullets in it. It would not auto forward with an empty magazine no matter how hard I would slam it in.
Another thing I noticed. When I would move the slide back and either have it lock by itself with an empty magazine in it or when I would manual lock it with my thumb, the slide lock would look like this:
The slide lock would barely catch the slide recess. It would be enough to hold the slide open but when you hit it with a loaded/heavy magazine, the bump/momentum transfer would release the slide lock and the slide would go forward.
I started looking at the gun itself. I noticed that the slide lock lever tab inside the gun was angled ever so slightly upwards. Here is a picture of the tab. Picture taken after I did my modification:
The spring tension in the magazine pushes the magazine follow up. When the magazine it empty, the magazine follower pushes up on the tab and therefore the slide lock lever goes up. This in turn locks the slide back when the slide lock catches the slide recess.
My solution was to move the tab down a little bit. I tapped it a few times with a small brass armorer's hammer. Just enough to bend the tab down slightly. This makes the slide lock lever move up more. The slide lock now looks like this when I manually move the slide back or when the gun runs empty after the last shot.
Went to the range yesterday and shot the gun. No auto forward when inserting a new magazine with normal to moderate force. I fired 200 rounds and the gun operated without a hitch. Obviously, I'm planning on using the gun more. If I run across anything new, I'll keep you guys posted.
Hope this helps.