M&P15 Sport, supplied magazine not staying in..

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MedWheeler

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I bought my M&P15 Sport last summer, but have not yet shot it. Handled it quite a bit to become familiar with it, but just have not yet gotten to an outdoor range (40 miles or so to nearest) to try it out, and don't wish to at an indoor pistol one.

Took it out today to handle it some, and noticed the P-Mag supplied with it can be pulled out of the well without hitting the release. A second magazine I bought after getting the rifle, a ProMag, does stay in, and requires pressing the release to remove it.

The P-Mag slides out when pulled regardless of whether or not there is ammo in it. It doesn't fall out but, as mentioned, can be easily pulled free.

I don't remember if I tried this when I first got the gun, so I don't know if it has always been this way.

What say you? Should I try to source another P-Mag?
 
UPDATE:

After typing this, I tried again, and it locked in for two attempts, then failed again.

After several more times, I noticed that I can lock it in (sometimes) by giving it a quick and vigorous front-to-back shake just as it seats, and there is a distinct click I hear that tells me it's seated and locked. If I don't hear that click, I know before trying it will pull free if tried.

Probably needs some more swift break-in seating, perhaps.

I'll also call Smith and Wesson; maybe they'll send me another magazine to try..
 
Look at the magazine release button, in the center does the pin look flush, or protrude a tiny bit, or is it recessed in the center of the button?
 
It's not uncommon to need to give a full mag a nice whack on the bottom with your Palm. Like in the movies... but Empty that shouldn't be the case. If a light tap sets it I would not worry about it. I have had some p mags that had a little extra plastic at the top. A couple strokes with a file on each lip fixed it.. but you need to determine why it isn't seating first. Like previously mentioned make sure your mag release doesn't need another turn or two
 
I have the same issue with my only Pmag. It needs a good whack on the bottom to get the mag seated. My D&H mags lock in with no problem. I prefer the aluminum mags.
 
There's a reason most folks only load 28 rounds in their AR mags... they're almost always too hard to seat on a closed bolt with 30 rounds.

Try 28rds, then let us know if there's still an issue.

EDIT - I'm completely making the assumption that you're doing it with loaded mags. Sorry. If you aren't, then I would get a hold of a couple different mags and try them. Could just be the PMAG. I wouldn't think a lower would be so out of spec as to not accept PMAGs, but I'm sure it's possible. Definitely let S&W know if your lower is the problem.
 
Yes you need to make sure the mag is fully seated. Push the mag in firmly and you may hear a click. But the acid test is you pull downward on the mag to make sure it doesn't come loose. If it does, push it back in firmly and test again. You shouldn't need to smack it. After a few times you will get the knack of seating the mag properly. (NOT like in the movies!)

The issue of loading 28 or 30 rounds (or 18 in a 20 rounder) is a debate that goes back to Vietnam. Back when (1960s) many issue mags were real crummy pieces of crap, you sometimes needed to download them or they wouldn't work. Those mags are long gone and modern types usually work just fine. Personally, I load them full. If it won't function there's something wrong with the mag or the gun.
 
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Thanks a bunch, guys. Glad to hear it's not just me.

I emailed S&W and asked if they were aware of any such issues, and offered to trade my mag back to them for another to try if they thought that might be the case.

We'll see what they say...
 
Inebriated, thanks. Yes, my mag is loaded. I did take two rounds out of it to put in the Pro-Mag when I tried that one (that one still seated.) Honestly, I don't remember if I tried the PMag with those rounds out. I'll try again tomorrow, maybe.
 
You shouldn't need to download that Pmag. If you're convinced you're seating it correctly and it won't latch in, then likely the mag is bad. Why give up 2 rounds if you don't have to? But personally I've yet to see a bad Pmag.
 
If it's a full mag and the bolt is closed. It will be tough to get it locked in. Does the OP have the bolt open or closed when trying to use the pmag
 
It shouldn't be very hard to lock in a full mag with the bolt closed. No smacking required. As allaroundhunter said, just Push - Pull.
 
unlimited4x4, I'm inserting the magazine with the bolt closed, as if loading the gun from a completely clear status (insert mag, cycle bolt to chamber first round.)

I have not tried yet to do so with the bolt open..
 
My preferred method for loading an AR is to lock the bolt back, insert a magazine and hit the bolt release to chamber a round.

You can insert a fully loaded mag with a closed bolt, but you need to push it in firmly.
 
Just bought my wife an M&P 15 Sport for her birthday. I ran 200 rounds through it when I was sighting it in. (Obviously I was having a wee bit of fun...)

Not one problem with any of the magazines, including retention.

If you're having a problem with the one that came with the rifle but not the others you bought, I'd say that's a pretty good indicator that you have a magazine fault. Please post S&W's response. Magazines are cheap, and I'd be surprised if they didn't just ship you another one and ask if that solves your problem.

Good luck!
 
The Pmags fit tight when inserting with the bolt closed. Just apply firm pressure until you hear the mag catch engage. Mine was just like yours.
 
Try the PMAG (loaded or unloaded) with the bolt open. If it goes in with an authoritative "click" every time, and you can pull against it and it stays seated, this tells me you just aren't applying enough "oomph" with a loaded mag on a closed bolt. With the bolt closed, the bottom of the bolt carrier is depressing the rounds in the magazine (the rounds in the magazine only contact the feed lips with the bolt open). To insert a full mag on a closed bolt you need to exert enough force to push the rounds down.
 
One of the issues with a load 20 rounds in a Nam era was sometimes the bolt would not strip off the top round. Could have been too much pressure on the top round against the mag lips or buffer spring may have been weak.
 
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