Problematic S&W M&P15?

[Greatestsin]

Yesterday, I went to the range with my friend who just bought a brand new S&W M&P15.

The first time he took it out, kept fouling up on the second magazine, couldn't go more than one shot without it failing to get the round out of the magazine.

He took it back to where he bought it, and they fired two magazines through it no problem.

After cleaning it (he cleaned the upper receiver and bolt assembly, and a little of the lower receiver by the trigger group and the mag well, didn't take out the spring cause he didn't know how) we shot it yesterday. 300 rounds through 5 pmags and two aluminum mags, and 3 times the bolt failed to lock after empty(always on a pmag not on the aluminum). After that the next magazine did fail to pull up a round twice towards the end, and the next magazine did it almost every shot, and the magazine after that did too.
The bolt sailed right over top the round most of the time this happened, but a couple of the times is caught the round but the round got stuck on the feed ramp.

The gun was nice and wet when we started and stinkin filthy when we stopped after the mishaps. Took us an hour to clean it (I volunteered my services in aiding his cleaning, but made him do the chamber) Removed the bolt assembly, dissassembled it and cleaned it up, the lower receiver got a touch up, pulled out the spring and cleaned it up, and he cleaned the upper receiver.

We are going again next wednesday to see if the problem persists, but S&W phone customer service said its part of the break in period. What do you guys with experience on the M&P think, since the only AR I ever owned was a problem-free armalite?

 

[243rem700]

Do the problems happen with all of the magazines and different brands of ammo?

 

[shooter521]

https://www.indianagunowners.com/fo...expertise_needed_ar-15_issues.html#post699131

 

[Greatestsin]

All the mags yes and the only ammo tried was 50 grain PMC FMJs, on another forum i was given the suggestion to try better ammo and see if the problem persists. Apparently S&W had a bunch of the rifles go out with the wrong gas port and that could be an issue apparently so I might suggest he send it to S&W to get checked out for that.

 

[Defensive Shooting Concepts]

To me it sounds like the Mags are not seating correctly in the rifle. You stated the bolt did not lock back and that the bolt also closed without feeding a round in the chamber. To me I would start with Mags and see if they are correctly seated in the rifle.

 

[GarandMD]

I agree that the mags may be the problem. As an owner fo an M&P15T I think I remember reading that early M&P 15 mag wells had trouble seating early Pmags. Both were later modified so that the problem no longer exists. I am sorry that my memory is a little hazy on this. A quick google search brings up a lot info on it however. Though new, are the rifle and Pmags an early vintage?

 

[Greatestsin]

The Pmags are the generation with the dust cover, but it doesn't snap to the bottom. No window on the side. The M&P is brand new, we would assume a newer generation. I'll have to have him find out. The problem occurred with the aluminum magazines too.

 

[ngonerogwu]

Wow, I've never had a problem with mine. I've got the M&P15 MOE. Never had a failure to anything...

Mine came with a windowless PMAG.

I have 3 windowed PMAGs that the dust cover attaches to the bottom, and 3 windowed PMAGs where the dust cover doesn't clip to the bottom.

I've also shot it with a GI mag, but I liked the pmag's so much better, i dont use the GI one much.

 

[U.S. Patriot]

I agree that it sounds like the mags are not fully seated. Did you give it a nice tap on the bottom, to fully seat them. As a previous poster said, with the bolt not locking to the rear and the bolt going forward over top a round. Could be weak springs in the mags, not putting enough pressure on the follower. Hence the round will not be siting high enough, for the bolt to pull a round out of the mag. I have had this problem with other guns, where the follower was sitting to low in the mag. You might try taking the mags apart, and see if you see a problem there. Or maybe try spraying a little dry lube, like rem oil on the mag springs. Also it could be an ammo problem. Some guns are just finicky with certain ammo. Hope those are some helpful suggestions. Hope things work out for your friend, and the problem gets fixed.

 

[jerp239]

Mine did this when I first got it, took it back to the gun shop and they did the same thing you said. They shot 2 mags through it no problem, turned out it was the steel cased ammo that I was using. I was using Wolf and they told me that until it is broken in not to use the Wolf. After about 1000 rds of breaking it in I can shoot the Wolf with no problem and haven't had any issues since

 

[Dryden]

I've shot some PMC ammo thru my M&P 15 without any problems. However, being made in Korea, who knows if the quality control is consistant?

 

[Greatestsin]

I have started a new thread about this gun:
https://www.indianagunowners.com/fo...troubleshooting_pic_intensive.html#post733267