Help with new M&P 10 - Failure to load next round

[Etrev]

Hello, new M&P 10 owner here. Wish I was joining the forum under different circumstances hah. However, I've encountered problems starting with the first shot from this brand new gun and I'd like some help.

I've had no problems with actual firing. The bullets hit where I aim, and nothing really seems out of the ordinary. However, despite the fact that that the shells are being ejected, the next round consistently fails to load.
I shot 11 rounds, checking the action and magazine for possible causes between shots. The only other thing I noticed was that I thought the felt recoil was pretty weak. I'm not a very big guy, nor have I ever shot a .308 before, but it felt quite dull to me. Way closer to .223 in felt recoil than say .300 WSM or .30-06 which I've shot. I decided not to worry about it, and try again with different ammunition later.

When I went to purchase different ammo from the same store where I purchased the gun, I mentioned the problem to them. I asked them about the possibility of changing out the gas block for an adjustable one if the problem persisted, as this is something I've read online and around here that plenty of other M&P10 owners have done. But the guy said that there was "no way", and that even if I did find a block, that installing it would void my warranty. This really confused me and started to make me worry.

I went to test the new ammo. It was more expensive, and they recommended it for the reasons I cited to them. Same thing happened, no semi-automatic fire. Only shot 3 rounds then gave up.
I'm really not too worried or upset about this at the moment. I'm actually pretty excited to own this gun and would just like it to function the way it should.
So help me out please. Is this an issue of the gas block or some other feature? And if it is the block, can it be replaced safely and problem free contrary to what my salesman told me?

 

[sgtsandman]

Is sounds like the action is under gassed and is causing the bolt to short stroke. Meaning, it's not cycling enough to allow the next round to be caught by the bolt so it can be stripped from the magazine and fed into the chamber.

There are adjustable gas blocks out there that you could get. The block diameter is .750, though I would verify that there is no left over metal from machining blocking the port or the gas tube first before spending any money. You could also open up the gas port in the barrel as another option if the gas block doesn't work.

However, the person at the store is correct. I don't know if it just applies to the M&P10 or all of their models, but their most recent policy is basically telling us that if the rifle is not kept in it's stock condition, chances are not good they will honor a warranty claim. There is a couple of threads concerning issues with the rifle's barrel and getting warranty work done in the M&P10 section.

With that being said, it might be in your best interest to check with S&W first about the issue before you start doing any modifications.

 

[Etrev]

Thanks sgtsandman. If that's the case, I'm a little disappointed to spend over $1000 on this gun to find it's under-gassed from the factory, with no adjustable setting for gas, and a policy that objects to my using an aftermarket remedy.
I'll definitely have to contact them.

In the meantime should I refrain entirely from shooting it? The person at the store told me to gently play with the action for a long time and "break it in" before shooting it again. Does this sound like good advice? Any other possible recommendations?

 

[yqtszhj]

As long as it was lubed good when you shot I would call S&W and tell them your problem and that it happens with quality ammo. They should take it back and fix it for you under warranty at their cost. Do that before you spend any of your hard earned money on something you may not need.

I've fired hundreds of rounds through mine and the only time that has happened is with cheap turkish zqi ammo and it probably happens once per box. Every other ammo has been good to go.

If it is hitting where you're aiming you got a good one and let them fix it. JMHO

That being said I have a hard time taking my own advise so if you work on it yourself I would understand too.

 

[Tbat]

Sgtsandman, gave you some good information. However, since it is a new rifle, there is one more thing to look at. Did you lube the bolt before shooting the rifle? Just throwing that out there, as fortunately that is the only problem so far that I have experienced with new out of the box AR type rifles.

 

[yqtszhj]

.... However, since it is a new rifle, there is one more thing to look at. Did you lube the bolt before shooting the rifle? Just throwing that out there, as fortunately that is the only problem so far that I have experienced with new out of the box AR type rifles.

VERY GOOD ADVICE!

 

[sgtsandman]

I took making sure the bolt is lubed for granted. An error on my part. Since video or pictures are better than words, I would suggest searching youtube or Bownells on how to properly lube an AR action.

So far, I've only shot PMC, Lake City surplus, and Federal and Remington Match King ammunition. All of those have cycled fine through my rifle.

Shooting your rifle will loosen things up over time but having to manually operate the action every time would defeat the purpose of the design and would be a big pain in the dupa. I would still talk with S&W first before looking at doing any work yourself or spending any money on it beyond what you have already.

 

[Bassaro]

Put one round in the mag, chamber it shoot and see if your bolt locks open. If it doesn't lock back, Well then let me start the dog pile of people telling you not to do this even though it is what needs done to your rifle.

Your rifle is under gassed and the solution is not a new gas block but rather you need to have your gas port enlarged. Let me get one point across here though take it to a qualified/certified gunsmith. There is to much room for error on this one in your basement with a drill. I guarantee your rifle will run if you have this done.

Now comes the part where other members on here will tell you some nonsense about buffers, gas rings, type of ammo, or my favorite of just "It just needs broke in". To be clear break in is when you have a Failure to feed once or twice every mag or two. Break in is not FTF on every round. There is a post like yours on here very frequently but if you call s&w they will tell you "That's the first time I heard that one, send your brand new rifle back to us for three months". In all reality if you measure your gas port before you send it in to them I bet it's bigger when your rifle comes back to you...

Don't lose faith on this gun though man, after you get it running it will run any type of ammo.

 

[Etrev]

Thanks guys, certainly haven't lost faith yet, quite the contrary. I lubed the bolt up good and tried again, with partial success. I was finally able to fire off two consecutive shots, but I was still having the problem of feeding rounds. This made me question whether gas or the bolt was the culprit. Recoil was definitely more noticeable when firing back to back shots w/ the nicer rounds too.
My next attempt I applied pressure to the bottom of the magazine upwards into the rifle, and fired 10 rounds without a problem. Not sure what to make of this. Any thoughts?
I'm hoping to try with a new magazine at some point. My worries have subsided for the time being as I now have a functioning semi-auto rifle

Another thing I will mention was that I did contact S&W before my last attempt. I was surprised by how smooth and easy my experience was. And despite the fact that very viable other factors like bolt lubrication or magazine fitment were plausible causes, they asked no questions at all and immediately offered to send me a shipping label and sort it out. Glad I don't have to send it out, but good to know that if I ever had to that it seems dependable.

 

[Bassaro]

Glad to hear it man the stock mags are on the crappy end of the spectrum. Get some Pmags, they run like a champ in everyones 308s. I think you would be hard pressed to find anyone who has had a issue with them.

 

[yqtszhj]

The new guns come with pmags. At least mine did. I'm not at home or I would check this on the M&P and I've never had to do this on an AR platform I own but isn't there a way to adjust the depth the AR mag seats? I believe there is. Maybe pull out a lever opposite the mag release button and give it one turn? I just cant remember.

Edit: Found it. Dont know if the M&P 10 does it but the Bushmaster has a way to adjust the magazine catch for FTF problems due to mag not seated properly. Push the catch button on the right, adjust the catch on the left, turn clockwise to tighten, counterclockwise to loosen. Like I said I'm not able to check mine now so not too sure if the S&W has this. If you need pics of what I'm saying download a Bushmaster AR15 manual and look at ftf problem resolution.

Hope this helps maybe.

 

[Tbat]

Etrev try some different mags if you haven't already. I have read about some bad Pmags occaisionally but I have not seen a bad one in person. Pmags are my first choice for .308 AR mags. I know on both my MP 10 and a DPMS Gen 1 .308 that I did have, that the metal mags that they came with were a little quirky, although they began to work better with use.

 

[sgtsandman]

It seems you may have narrowed it down some. Like others have said, try a different magazine and see if that works. The adjustment mentioned above might help too. Mine runs fine with the stock mag and 20 round versions made by the same company but they can be a rough. Pmags are certainly a better magazine to run and load compared to the stock ASC magazines.

 

[tdapsr]

The stock steel ASC magazine is a piece of $hit. I had nothing but problems with it.....Including falling out of the mag well upon recoil. Mine cycles flawlessly with the Magpul Pmags. Try that FIRST.