Smith and Wesson M&P 10 not cycling properly , JP H2 silent will help?

lucsergerie

lucsergerie

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Hi Guys


I have a Smith and Wesson M&P 10 .308 that doesn't cycle normal rounds, it cycle only hot load 180+ grains it is a well know problem at S&W and they don't care to much, my mistake was to not shoot the riffle stock, i add a new hand guard and gas block.


-Do you guys think that a JP silent buffer H2 will help? ( i think the Tube different on the M&P 10)

My last resort will be to drill the barrel and add a adjustable gas block :(


Thank you
 
lucsergerie said:
Hi Guys


I have a Smith and Wesson M&P 10 .308 that doesn't cycle normal rounds, it cycle only hot load 180+ grains it is a well know problem at S&W and they don't care to much, my mistake was to not shoot the riffle stock, i add a new hand guard and gas block.


-Do you guys think that a JP silent buffer H2 will help? ( i think the Tube different on the M&P 10)

My last resort will be to drill the barrel and add a adjustable gas block :(


Thank you
Click to expand...

if you put a new gas block on I would think that's were you need start looking. I would guess that its slightly out of alignment or has the wrong sized port causing your under gassed cycling issues.
 
If its undergassing, a heavier buffer wont help at all, you are gonna make it even worse.

Hows the brass ejection pattern? Just kinda drops out of the ejction port? Or does it fly out towards the front of the rifle?
 
Then its undergassing. If its a factory rifle, send it to the warranty center and they should be able to fix it for you. If its a franken rifle, take a drill bit and open up the gas port ever so slightly, dont go full speed and do like 5 passes.
 
Put it back to factory. That way you can do a diag to see if its the new gas block that is causing the problem. Hand guard shouldnt be a problem as far as warranty goes
 
Measure hole in barrel measure hole in original gas block then measure new gas block this can be done with numbers drill bits by hand.
 
do not do anything to the rifle, send it back to the factory for repair. let them fix the problem and replace parts if necessary, if you try to repair it they will not honor the warranty if the problem is serious.
 
barsik said:
do not do anything to the rifle, send it back to the factory for repair. let them fix the problem and replace parts if necessary, if you try to repair it they will not honor the warranty if the problem is serious.
Click to expand...

Except he took off the FSB and put in a gas block...
 
go on ar1x.com find the related measurement of an ar10 barrel in your specific setup ( ie16inch Car gas/ 18inch mid gas), and see what size gas port it should have, then drill with corresponding drill bit. Worst come to shove is that you may need a few drill bits and an adjustable gas block after.

also make sure that the gas block you have is of correct size for that barrel, ask me how i know :(. i have once out an .875 on a .750, and for the life of me i was in the same boat as you are.
 
Sky52 thank you for your imput , I just order a JP gas block , i just read many post on the M&P 10 and nobody agree on the space between the block and the barrel? some have luck with no space! i used 0.25.
 
Space between the gas block and the shoulder should be about a credit card size thickness to account for the hand guard cap.

Some people do not need space between the 2 is because some gas block have an over size pick up port in case of misalignment and or installation error. Thats why your mileage may vary.
 
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