From slide lock when a mag is inserted the slide automatically releases and chambers a round. This is a brand new M&P 9mm I bought for my wife last November. It only has 400 rounds total and its already happening. I’ve seen it happening to other pistols (tired range rentals) but this is the first that’s in my family.
Is it due to an out of spec slide stop or spring?
I have had a CZ and a Glock do this, but not consistently. It would happen when I was slamming the magazine home too forcefully, which jarred the slide lock.
A couple of questions - How forcefully are you putting the magazine in the well? Does this happen all the time? Has it been doing this from the start?
This has been discussed on here before. Not a big deal and most if not all M&Ps do this. Most Glocks do as well if you smack the mag home with authority.
I can’t get my M&P to do it, but most of the Glocks Ive seen will release when hit hard.
In my opinion it’s not a bad thing.
Many semi-auto pistols will behave this way, especially if hit at the correct angle in the correct spot.
It’s not a cause for concern.
Just don’t come to rely on it happening 100% of the time.
It seems to be pretty inconsistent. Whether the mag is smacked in forcefully or not.
Its my wife’s gun. She’s just gotten into shooting (4th range trip) and is getting familiar with handling and shooting a handgun. I taught her to press check everytime and not rely on that dropped slide to have properly chambered the round.
I know its not a bid deal for most but personally, I don’t like it. I prefer a gun to act only under my own volition. We’ll see how it goes. If she doesn’t like it we’ll send it back to S&W to see if there’ s permnant fix.
The “permanent fix” is to insert the magazine with out trying to slap the piss out of it and at a straight angle into the mag well.
If you insert the mag more forcefully then required and seat it at an angle towards the front of the gun (EG: your hand is striking toward the rear of the base pad and moving towards the front of the gun) this will occur. It also occurs with Glocks and HKs. Not a big deal. Seat the mag correctly and it will not happen.
I dont’ believe there is such thing as incorrectly slapping a mag into the mag well. Esp. if you have to execute it under stress ie. competition, training class, or heaven forbid a life and death situation. Its either in there or its not. I encouraged my wife to handle her gun deliberately and with confidence. (she’s not slamming it in with all her might) The slide dropped sometimes even when she or I tried easing it in as well.
I noticed it happens more when you slap the mag in striking the rear of the mag/rear grip backstrap area. If you slap it in with your palm more on the front of the mag it happens less often (slide moving forward on its own)
So there is no permanent fix for this by just changing out a part or spring? Its just the way certain pistols are regardless of make or design?
Most pistols will drop the slide from lock if you give them a sharp blow on the very back edge of the frame (behind where the magazine sits) at a 45 degree angle.
All of this is driven by spring pressure. Spring pressure pushes the magazine follower up to push up on the slide lock. When the slide cycles the tension from the follower pushes the lock into the slot in the slide of the weapon. When the slide begins to return to battery under the tension of the recoil spring it slams into the lock and stops. If your mag spring is weak and it’s just barely getting the slide lock into place and if your recoil spring has lost a bit of it’s zip, then the engagement between the slide and the slide lock might not be very solid…meaning it won’t take much of a bump to release the slide. If, on the other hand, you’re using a nice, stiff new magazine spring and a nice stiff new recoil spring the engagement between the slide and the lock is likely to be very positive.
If you’ve got a 20 pound spring on a 1911 bumping it isn’t going to drop it from slide lock unless you are “bumping” it with a sledge hammer.
All of this varies from platform to platform and from person to person. I’ve put thousands of rounds through my M&P’s (My 9 is well past broken in) and they don’t do the auto-drop from lock on me. If I deliberately bump the bottom edge of the grip sharply at a 45 degree angle it will drop the slide from lock but other than that they stay put. When I insert my magazines I tend to push straight up so that when the magazine locks in the heel of my hand is perfectly perpendicular to the bottom of the magazine’s floorplate. That’s just how I learned to do it and even when reloading in a hurry I don’t drop the slide from lock.
Because of physiology or training some other guys tend to push the magazine home using a more curved motion that has the heel of their hand traveling in an arc rather than a straight line up. Those guys may find that they drop the slide from lock automatically sometimes. I’m willing to bet that your issue is probably a result of the way you reload the handgun. Try slowing the whole process down and really watch how your hands work when you do the reload.
One of my M&P’s do this (full sized .45). My other 4 plastic guns don’t (2 M&P’s & 2 glock 19’s).
With the magazine going straight up with any significant amount of force, the slide will be released automatically. I don’t like it because, IMO, it’s not normal.
When this happens, I remember the first round in the mag would sometimes get stuck at an upward angle (nose against the upper inside of the back of the barrel) as well.
All four of my M&P’s do it when i do a speed reload. When I load them normally, they don’t. It doesn’t bother me at all, since my intent is to fire the weapon. If in doubt, press check or check the chamber loaded indicator (hole).
Patient: “Doctor, doctor! It hurts when I do this!”
Doctor: “Stop doing that.”
The problem is that your beliefs are in conflict. You believe the gun shouldn’t auto-forward and you believe you should be able to insert the mag however you want. Doesn’t work that way, especially (though not exclusively) with polymer-framed guns.
My M&P has done this once and I was probably slamming the magazine in (reload during a drill at class). My USPs do this when the mags are put in with authority (not necessarily slammed).
Interesting. We’ll try that at home with dummy rounds. Thanks for your insights.
Tens of thousands of rounds through various Glocks, 1911’s, HK’s, SIGs, Beretta 92’s etc and I never owned a auto pistol that did that until now. Not a big deal when its a range rental but its just a bit disconcerting now that its happening to “one of ours”. In other words I’m just not used it is all.
I’ve had it happen personally and seen it many times with students’: Glocks, HKs, SIGs, and Berettas. Though, as I mentioned, primarily it affects polymer framed guns. At least one large LE training center actually teaches recruits that it’s a viable option as an intended way to drop the slide … something I’m still not comfortable with, personally.
Short answer, “NOPE”.
I have had this happen at one time or another with just about every make auto pistol I have shot over the years.
If you don’t assume it will happen, it’s not that big of an issue.
The LAV yelled at me for doing speed reloads like this. I solved the problem by switching to my S&W 686 for the rest of the day.