I finally got to the range to fire the 10.. Before I went, I swapped the hand guard for a quad rail... Had to replace barrel nut and remove the gas block and reinstall... I was able to shoot 5 rounds.. brought the target in and put it out, shot 2 more, then the 3rd never went into the chamber... click (dry fire) check and no round... remove mag (Pmag) and reinstall charge handle and good, next round does not cycle...

I am leaning to gas block not aligned, but not sure since 7 rounds fired no problem and now won't cycle.. I even switched to a new pmag (20 round) loaded and first shot good, but did not chamber the 2nd round. I packed up and wanted to check it before I went more.

Few thinks to list:

I did not fire it from the factory new (I know, mistake)
I did not magazine 1 round to see if the bolt stayed open (I know, mistake number 2)

Just to move forward, I am looking of some input..

Thanks guys.

Aaron

Are you using nato rounds? If i use reg 308 rounds i dont have problems but with nato rounds it doesnt feed correctly, thats my problem atleast. Just wondered if you were using nato or not. I think my problem is magazine related. Cheap metal asc i got i was skeptical right out of the box with

Acrawc, you answered your own questions..........

Aaron, I would suspect the gas block first. Keep in mind the gas block does not seat all the way back against the shoulder on the barrel. If you remove the handguard cap the gas block needs to be off the shoulder the equivalent thickness, usually around .015" or so.

What ammo are you using? There is some **** stuff out there that won't work well in AR pattern guns.

__________________
Cliff
CCSO, FPD ret, USN ret.

Thank you for the replies. As I kept thinking, I have the gas block messed up.. I did not leave the space foe the hand guard plate / mount. I am almost certain this is the issue..

Also using the attached picture ammo:

Attached Images

ammo_2.jpg (56.2 KB, 372 views)

Sounds like you got it.

Don't count out the ammo. CBC has reports of not functioning in other AR pattern .308s on another forum.

$40?? is that for 20 rounds? Wow, I haven't bought ammo in a while.

__________________
Cliff
CCSO, FPD ret, USN ret.

It was for 50 rounds ......

Im having the same issues using the same ammo!!! Mine was 38.50 for 50 rds

Did you do any mods or is it factory?

Factory, pmc ammo shoots great no problems... Have problems with nato rounds it seems, those are nato rounds you bought along with what i picked up and some other nato stuff i have.

What NATO ammo are you Gents using? I've run Lake City LC66 through my M&P 10 with no problems. I also have some WCC and TW that I'll try in the near future. Come to think of it 60s vintage LC Match runs fine too.

__________________
Cliff
CCSO, FPD ret, USN ret.

Picture above shows the Box of ammo....

I adjusted the gas block today and blew air through and lined it up the best I could and have to say that from where I started and where I am now, I did not notice a significant difference in the sound of air.. BUT I know, range time will tell.. I am not optimistic, but will bring a different brand with me. Suck because I was stocking up on this before the 10 arrived, so I have 300 Rounds....

Maybe new Ornaments for the tree next year. Wife would love that!

Attached Images

ammo_2.jpg (56.2 KB, 144 views)

Im running the same ammo as pictured above. Along with some atomic ammo match grade 168 grain noslers, loaded in once fired military brass

Put 50 rounds down the range today with not one issue. Shot 40 rounds of the above picture (started the same way with 5 shots, Bring in target sent out and 5 more rounds). Up the other 30 down with no issues. The shot some federal eagle

Looks like gas block alignment was off. I am very relieved.

Also wanted to note the powder is pretty dirty

Good to hear may have to mess with mine before i go back out.

But cleaning is one of those great joys of owning a AR type rifle. For some hours of cleaning with ****** GI tools to get rifles "white glove clean" was a right of passage

Good to hear you got your problem sorted out. I have some CBC/Magtech ammo I bought for plinking with my Savage 10 and it gave a sticky bolt and wouldn't extract, had to use a rod. Apparently this is not unique with Savage rifles and CBC so I have 49 left. I'm going to give it another shot in my 308 Garand.

I have also bought an MP 10 and took it out to range right away with all factory hard-wear, did not change anything yet, SAME problem, almost every shot, round would eject, not pick up the next round, thought it was the 10rd MP10 mag I had, changed it out to magpul 20rd, same situation, I have been over every inch of the gun everythings good,(bolt,buffter ect..) changed ammo 3 times. Did you end up fixing your gun completely by moving the gas block? Doing the repairs is not the problem, Working on I gun I just bought IS. before I send it back just would like to know. thanks (magtech M80 was by far the worst)

My gas block adjustment seemed to fix the problem... I also think throwing some rounds down range helped things loosen up a bit!


How many rounds have you put through so far?

About 120, most has been magtech cbc m80 ball ammo 2012 production. Everything I've shot has been 7.62x51 NATO so far, switching to AE 308d this weekend just to see what happens. Your now shooting the mag tech with no issues ? Been getting a lot of questions about the ammo but have no opinion yet Bc of the problems I'm haveing

Same problem. Rounds won't eject completely. The gun is short stroking. Only Pmc 308 works out of prvi 308 168gr hp bt match, prvi 165 gr spbt 308, CBC 7.62, and portugese 7.62. I've shot 10 to 20 rounds of each of the aforementioned.

I took my MP 10 down to long competition saterday, I put 500 rounds down range without one problem, the gun needed to "break in". I have about 800 rounds through the gun and at 150 it started working perfect without changing anything, sAterday I shot the same magtech m80 I had trouble with 250rds with out one jam or short stroke. Ran about 4 different kinds of ball ammo then Switched over to match grade after that but this gun is very accurate at over 600 yards, I also used sig sauers tb-25 on the bolt and that seemed to help. So anyone with problems I would try to get up over 100 rounds before You get mad like I did , it's really a awsome gun.

I think people forget that this is a thing. Like cars, break your firearms in guys, as RR556308 said, this is an awesome rifle.

Ill try what you say, but a brand new gun usually does not short stroke every shot on most ammo types.

Its getting more reliable. Around 130 RDS now. Today I shot 30 and had just one FTE. Definitely grease the gun well.

This is a must, even more so when brand spanking new. I've noticed this metal is thirsty. Soaks up the CLP nicely.

yeah i got mine out of the box last week....short stroke... put about 50 thru it cleaned it... another 50.... SS still tried to realign gas block SS on every other round tried diff ammo mag still does it...im at about 150 rounds

yes this is one thirsty gun.... drinks CLP

think im goin to grease..

i got another 50 to try then its goin back

So far CBC sucks, prvi 308 165 spbt works always, and portugese 7.62 works always, and Pmc 308 147 works always. The 'always' is after my first ~ 150 rds

Please elaborate.....
I haven't fired mine yet, and would appreciate any explanation of this " gun well " statement.
Since this M&P10 is my first foray into large bore auto-feeding guns (-or- any AR patterned guns at all) I have less experience than I'm comfortable with about the initial level of lubrication expected for reliable operation.

Strip and clean the gun before shooting for your first time. Grease the four rails on the BCG that contact the upper receiver. Also grease the bolt contacts, cam pin, and cam pin slot. I lightly grease the lugs even though its not needed.. Also one drop of clp on the gas rings. I use tw25b, and put just enough grease on to see a little white ( but not on the lugs, just a very little). Regarding the lower parts, a light coat of whatever oil or grease should help on the contacts. https://www.google.com/search?q=grea...nf8Ycwju7qM%3A

I finally got mine to the range this past weekend. I have to say I was a bit worried with the reports of short stroking. Fortunately, I did not have any problems with it functioning properly. I was shooting winchester white box 7.62 x 51 147 gr.

I did clean my rifle before ever shooting it. I found no grease at all, just a lot of oil. The buffer tube/spring seemed completely dry and I did find one small metal shaving inside the trigger area. Not sure if this helped any, but I cycled the bolt about 50 times before taking it to the range.

I would not send my rifle back I know it sounds crazy but 100 rounds is not broke in get above this 150 -200 , every round short stroked in my gun at first changed nothing and now it runs great, runs magtech m80 with NO problems at all , also working in the industry, sending guns back not the best idea right now, I can't speak for smith and wesson but MANY are so backed up you may not see your rifle for awhile.

Thanks for the info on lub points. I am new to ARs and really have no idea where all of these points are, but I am sure I will find out. I ordered the M&P 10 from a local retailer on 4/5. How long did it take for you all to get yours if you had to order it?

Gunbroker. Took a week. Slightly unde msrp

That's reassuring, I guess. Maybe I wont have to wait till June to get it. *fingers crossed*

actually, I'm not arguing, just giving an account of my experience this past weekend:

when I installed my LP gas block (troy), I, too thought it needed to be set out from the shoulder the equivalent of the thickness of the handguard cap...when I installed it this way, it short-stroked...once I set the gass block against the shoulder, I've yet to have another feeding problem (although I've only put an additional 40 rounds through it, but still, no failures.

an armorer friend of mine told me that the holes in the LP gas block are designed to "match up" to the hole in the barrel when the block is seated against the shoulder (they assume that if you're installing a LP gas block, there most likely will not be a handguard cap present), at least this very much seems to be the case with the Troy LP gas block

see my home, home on the range... for details... but shot 80 rounds through mine yesterday with 3 types of ammo... the only failures to feed i had were the very first round, and 3 out of 20 of hornady steel match. all from 10 round asc mags. the 3 hornady failures the bolt just nicked the rim and scraped the side of the cartridge leaving an empty chamber.

Same ammo, same results. I feel a little better after seeing these posts and I'm not the only one. 90 rounds no change, now I have lubed up good but not Happy with this type of performance. Don't like having to go back and slop on grease to get a rifle to work. Ammo too expensive to have to do this.

When back to the range,5-11-13, greased up and 60-70 rounds with NO problems. A check of the bolt before I started showed it had absorbed a lot of the oil I had applied. Left it alone and started firing and boy am I happy now.

I am VERY intrigued by this claim, and would like some more information, I just put a troy lopro and a free-float on mine before i fired a round.

just stripped mine back down and noticed one of the two set screws on the troy low profile gas block is in direct line with the gas port.
I just spun the block upside down and peered in through the set screw hole the determined that a specially calibrated and certified razor blade is the perfect space required.
Spun the block back around drilled dimples for the set screws, loctited, and called it done

Hi All, I'm glad I found this forum, and I'm glad I'm not the only one that had this problem. I bought my MP 10 in May and I finally got to shoot it last weekend at the end of Jun. I was never able to fire more than 2 rounds in succession without the gun failing to feed. I had stripped and cleaned it right after I bought it. I was also using factory Federal with Sierra bthp 175 grain ammo. While on the range we field stripped the gun and oiled everything up again so that it was dripping. When we reassembled it, it still would not fire more than one or two rounds without failing to feed. One of the game wardens at the range looked at it and said that he thinks it might be something with the ramp and the cartriges were hanging on it. I may not be the brightest bulb in the batch, but I figured I was out of my league with this, and it should fire out of the box. I sent mine back to the factory with the magazine to have them check it out.
I did pull out a couple rounds that were jammed between the bolt and the chamber and they were pretty dented and had some deep gouges in the copper jackets.
I don't know what they will do at the factory, but I'm sure this will be a learning experience. I grew up with shotguns and handguns. This is my first foray into rifles.

Okay, did the rifle fail to feed these rounds which were scarred up, or were they fired and then the brass was gored on the extraction?
If the round was unfired, then look to the magazine, the ammo in it, and the feed ramps.
1. Magazines are so fickle some of them. If the rifle is feeding erratically, the magazine may not glide the follower very smoothly. The tiniest bit of slowing can cause FTF. The other side of this is short stroking; if the bolt does not retract all the way, then the chamber is open too short a time to allow for the round to feed into the chamber and be picked up by the bolt.
2. Some ammo's are too long to feed properly. With a 223, the 75 gr. can have issues, and by 80 gr. you are in general a single shot rifle. I have seen some heavier, longer 308 give issues with this. Usually, 150-168gr are flawless, so unless you are shooting 200gr, this is rarely an issue.
3. If the feed ramps look lousy, then they are suspect. Usually, feed ramps are good enough that you should not have much issue. People quit screwing around with sloppy feed ramps a long time ago; they are usually wide enough to accept ammo well, and usually are smooth enough to allow smooth feeding.

If I were to guess, a buffer tube weight increase of as little as 1/4-1/2oz might do the trick to slow the bolt down. Heavier bolts have a longer dwell period, when they are essentially stopped when the bolt goes all the way back. A lighter buffer weight will allow the spring to operate too quickly and your bolt will run over the ammo rather than pick it up.

Good luck with it!

Rojodiablo, all the brass, fired and unfired was scratched up. The unfired brass were the ones with the dents and heavy burrs on them and the copper jackets.
I returned the spare magazine that I bought for the rifle in case it was having the same issues. Both magazines were hard to load and the ammo didn't seem to want to come out without a lot of effort.
As far as the buffer tube, hopefully the professionals at Smith & Wesson can make that call.
Thank you for your insight.

Just an FYI for anyone that is thinking of sending their rifles back to S&W for warranty work. I called today and they told me it usually takes them about 3 weeks before they can finish and ship the rifles back to us. I still have to wait a couple more before I can go back to the range now.
24 July 2013
Feedback from Smith and Wesson was that they repaired the barrel and replaced the magazine. That was all they had on the sheet when the rifle was mailed back and all S&W customer service could tell me when I called in for details.
Maybe I can do some plinking this weekend.

Does anyone know how to locate the gas block?

locate as in placement ?

Albuquerque. I saw one there. Was with Bugs Bunny. He said we shoulda made a left turn......

I will mark the barrel with tape, or a fine pencil for the depth of the holes. If the old unit left a wear mark, then it's easy to get the 'depth' of the end of the block to the hole. I tend to put the upper in a vice, sandwiched between a couple pieces of wood and get it level- left and right, not fore to aft. Then, it's all a visual, and pretty easy. I use pencils, and make marks. It helps get it all in the right places.

Same problem. New AR-10. Have cleaned and oiled it but still won't feed ammo. Have tried several different brands. On the last round it won't stay locked back either so I assume it has to be short stroking. Bought the Magpul version from the factory so I haven't added anything. Any suggestions appreciated. Very frustrated and don't want to have to send this back to the factory.

Keep shooting it.. Put 300 to 500 rounds through (clean and lube frequently... I like Frog Lube) and then see what it does....

I had the same issue with my rifle when I got it as well. I am a reloader and found that the only rounds that would somewhat cycle were max loads. It's no great surprise that some guys are having success with PMC as it is a hot ammo.

You then need to have the gas port increased in size slightly. Everyone has guesses as to what the problem is; why is everyone not addressing this as the solution. If you mic the gas port on a smith it is crazy small when compared to other 308s in a ar format. You don't need to go over board or even match the size of the port on a LAR or anything like that but the truth is smith made it to small and you have all these M&Ps short stroking out of the box. People sent them back to smith who my guess is drilling the gas ports bigger and sending them back.


But make sure you go to a qualified and certified gunsmith who specializes in military rifles or at least has a good bit of experience with them. Joe blow hunting rifle gunsmith in most cases knows less about a AR operation then you do and that is the truth.

The whole run 500 rounds through your gun to break it in is BS as well. All semi's do need broken in and that is the truth, however this should be done at the 100 round mark 200 at the max. Once again I am a reloader and find 308 expensive I can't even begin to imagine how angry I would be if I wasn't running reloads and wasted all that money on factory rounds to "break in" a rifle and then find out that's not even the problem.

Anywho that's rant...seriously though anybody reading this thread find a CERTIFIED military type gunsmith and have them do what I said , It WILL fix the problem. But make sure they are qualified as this is not a garage style fix and could seriously damage your barrel if done wrong. I believe having this done only cost me like $35 too...which I believe is cheaper then 500 rounds "break in" ammo...