Well took my M&P 308 out last Sunday and it would not {cycle} load or chamber a round at all, tried different ammo, mags so on. It would NOT work, well I called S&W & he said to use 168 and higher grain like 178. Well I tore the gun down and used gun grease instead of oil, today I went to the range today and man that gun ate every bullet I could throw at it . So use grease instead of oil to lubricate.

My M&P's won't separate the glass and plastic from the organics either. -





Glad you got her working.

Mine likes lubrication too. Glad you got it running.

Has anyone tried using a reduced power buffer spring to solve the short cycling issue?

I had the same problem last weekend. Just needed to lube it up!

I am having the same problem but my rifle has had no problems until today , I have been using the same ammo and have never had an issue until today. I load the page and chambered a round and shot it but the bolt did not move and when I tried to manually eject the bolt was very hard to pull it back almost like the bolt was binding??

I know it is a bit of a thread hi-jack but since lube was the solution I don't think the OP would mind.

My short stroking issue was resolved by just shooting about 200 - 300 high pressure rounds. What I mean by high pressure is full power hunting rounds. After that I can now feed any kind of bulk ammo and it cycles just fine and runs like a sowing machine.

Since the M&P10 was designed for hunting the buffer spring just needs to be run in with that ammo. Before I did this I had some milsurplus and that rifle would short cycle like mad.

They are somewhat undergassed for less than prime US full power hunting ammo. On the edge I would say.

Taking the gas port from .068 to .073-.075 will cure that.

Lube it like oilmcost nothing.

I'm having a similar problem. I suspect it's the ammunition though. I bought 260 Freedom munitions 150 grain fmj cartridges. Took the M&P 10 out to the range and it would only fire one round at a time. I figured it was the mag (brand new pmag) so I changed it. Same problem. Loaded some 155 grain a-max freedom munitions cartridges and it ate them up. Same as 150 grain Remington soft points. Strange thing is that the fmjs have a higher advertised muzzle velocity than both of the other rounds. Not sure if I will change out to a lighter buffer, install an adjustable gas block or take it to a gunsmith and have them enlarge the gas port on the barrel which I think should be a last resort. Any suggestions?

I am having a similar problem also. My first mag usually runs flawless, any thing after that is single shot. I bought a 250rd can of LAX 168 grain poly tips and have tried three different times. Today I stopped and picked up a box of horniday 165 hog rounds, and a box of 150 winchesters. They both ran smooth but the hornidays blew one of the primers out and every case looks like a someone tried to turn it out with a screw driver. The winchesters seemed to run ok.

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Robin

From experience I concur with the gas port being too small, tried buffers ..springs still band-aid to the real issue not enough gas to push the lock the bolt after last round for anything less than 168 grain, the fix is open it up and add an adjustable gas block. For the S&W rep to state this tells me they know about the issue and for some odd reason since introduction never fixed the problem. They should clearly state in the manual do not use anything less than 168 plus ..which kinda defeats the purpose of so called battle rifle ..in SHTF scenario I can see myself looking for 168+ grain only ammo lol ..come on S&W fix the damn thing

Have you tried SLP 2000 EWL for gun oil. Switched to this oil and haven't had any problems with any of my weapons since. I shoot 150 grain Hornady SST's and 150 FMJ's in my M&P10. Even up to 208 A-max with no problems.

Mine has eaten anything I've fed it. 149gr PMC bronze, 147gr Lake City 7.62NATO, an other rounds.

sgtsandman, I assume yours is factory stock, throw a muzzle brake on it and then try that ammo.

https://www.flickr.com/photos/118379003@N05/

I've used nothing but Slip 2000 EWL on my M&P 10 LE since day one and it hasn't had any problems whatsoever and shoots sub moa groups with both Hornady 165gr SST's and Australian Outback 165gr Gameking's. I also use Slip on all of my weapons and they are happy.

I have a Surefire ProComp brake on mine and it's feeding and cycling 150gr stuff ok. I'll try some other types of ammo this weekend, but so far no problems here.

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- Fourth Horseman -

The flash hider/brake that came with it is the stock one. Unlike my bolt rifle, I didn't see a need for a muzzle device with more braking action. So in that sense, you are correct.

Nice photo gallery you have linked, though I'm pretty sure that was not your intended link you wanted to illustrate. Not that I'm complaining...

Actually it was intentional Females with Guns what else is more beautiful

You're doing good work, sir. Keep it up!

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- Fourth Horseman -

Thank you sir for your support, ck this badass rifle

https://www.flickr.com/photos/118379...posted-public/

That magazine is huge! Nice looking rifle though!