MP 40L CORE Slide Closes when loading full mag

[Mike1161]

After shooting 400-500 rounds through my 40L I finally had a chance to try out replacing the mag quickly and getting back on target. I don't normally load 15 in a mag but did so this week. After shooting the first mag, dropping it out and slamming home a fresh full mag, the slide closed without me touching either the slide lock or the slide itself. I have seen an old Youtube about this issue but assumed that S&W had figured out the issue and fixed it.

I didn't get a chance to try it without a slam or a lesser amount of ammo, but it is disturbing that it does this. Anyone else have this issue or a fix?

 

[hkmiller]

I believe this is by design.

Sent from my SGH-T989 using Tapatalk 2

 

[jdh]

Have you read the manual?

 

[hyrulejedi86]

Mine does it, it's a 9mm 4.25" and i love the feature. I've always heard it was by design

Sent from my DROID RAZR using Tapatalk 4

 

[t1.8matt]

I am not a big fan of this either. Luckily my Shield does not do this, but I noticed today while at the range, my Kahr CW9 started doing this. Granted I don't have my finger on the trigger while putting in a fresh mag, I do not want the slide going forward until I want it to.

 

[jwalts27]

My 40 FS does the same thing. But my 9 doesnt.

 

[Don 73]

My issued Glock does the same thing

 

[jeffhughes]

Why would you not carry a fully loaded mag?

 

[Don 73]

Why would you not carry a fully loaded mag?

I'm just referring to fast reload drills during qualification, otherwise, I carry fully loaded.

 

[vaeevictiss]

I guess people will complain about something. I recently got an m&p just for the ambi slide release. I was upset when I found I had to damn near tear my thumb open to release it as a lefty.

Then I found out about the mag slam trick, and that is just the cats pajamas lol. So much nicer.

If you are worried about a negligent discharge, I wouldn't be.

Sent from my Galaxy S4

 

[forrestinmathews]

Take thumb off of slide release while seating magazine. Seat magazine gently. Enjoy.

Why would you want to heartily insert the fresh magazine and not have the gun go into battery? Sounds like you're accelerating into the stop sign...

 

[Mike1161]

This is not a CC gun (for me). It's a pistol I plan to use for local action shooting events. Having been shooting autos for many years, this is the first one that I have owned that does this. It is different and unexpected compared to ALL of the autos I have. Now that doesn't mean I can't or wont get used to it, but it is different. When reloading at a quick pace, I don't use a gentle touch to seat the mag since I want both speed and assurance that the mag has been seated properly and I am ready for the next shot.

I have re-read the Owners manual and there is only two sentences in it regarding using "excessive upward force" that "could" cause the slide to close. So it's not a feature of the gun, but a design issue. Good or bad, it is what it is and I will live with it. That being said, I wouldn't call it the safest design but it could be an advantage if time was an issue assuming you could depend on it happening all the time and in all conditions.

Just my thoughts.

 

[Rapidray]

I will have to see if mine does it. Has not so far.

 

[bobermo]

I would examine the slide lock lever position after the last round fired compared to you manually locking the slide. Maybe the magazine follower is not raising the slide lock lever adequately. Try inserting the mag after you manually lock the slide to see if there is any difference. Check the edge of the lever where it locks the slide. Maybe it is worn and not getting adequate purchase on the slide. I believe s&w also updated the slide lock lever spring. That may also play a role.

 

[MSG Glenn]

My M&P 40 & 40C both do that. That's a good thing. It's supposed to. It takes a pretty hard slam of the mag, though.

 

[Omenwolf]

Making a mountain out of a mole hill. I shoot uspsa and see a lot of reloads. 99% magazine fed pistols guns do this, remember its just a little spring and some tension from slide lever holding it in place. Hit it hard enough and its gunna move. Go and try it on your other pistols, no mag just tap the bottom with the slide locked open. Most people like it because it makes for a faster reload.

 

[hapns]

This is not done on purpose, and I believe it is mentioned in the manual-- something like "Caution: if you insert a full magazine too quickly (hard) the slide may release." If you like to send your magazine home with authority to make sure it's properly seated, this will probably happen. Just don't come to rely on it.
It's also nothing to be concerned about, as it is common with many semi autos.

 

[Mike1161]

Just back from the range. 200 rounds with 25 or so mag changes (less than 10 per mag) and it only did it twice when I really slam the mag home.

As I said earlier, if you could count on this happening all the time, then it could be an advantage, but if you expect it and it doesn't happen, then you loose time.

My gun has less than 1000 rounds through it so I wouldn't expect it to be due to worn parts, but I will have a good look at it when I install the Apex trigger this week.

 

[timjake]

My Pro M&P40 surprised me when it did it the first time, and yes, it was a full 15 rd mag. Normally I shoot 10 rds/mag even if they hold more (5 mags, 10 rds each = 50 rds per target). It's happened maybe 4 times total. I haven't had it happen with a fully loaded 10 rd mag.

 

[BIGMAC116]

I wouldn't call it an "issue to be fixed". I think its a great way to improve a combat reload times.