Smith & Wesson M&P 10 not running

[ar15barrels]

I recently bought a S&W M&P 10 and took it to the range to function test and sight in the Nikon M308 I mounted on it.
It fires 1-5 rounds the will either fail to extract or strip the round

Has anyone had this happen or does anyone have any suggestions?

When an AR type rifle will run good for the first 4-5 rounds of a new shooting day and then start having problems, the issue is usually the gas key fit to the bolt carrier.
Either the gas key or carrier are poorly made or the screws are not torqued on well enough.
To troubleshoot, swap a different CARRIER (only) into the gun, using your original bolt head and test fire it.
If the problem goes away, that confirms the problem to be within the carrier assembly.

What is happening is that the gas is leaking between the gas key and the carrier, causing short stroking.
A COLD carrier will seal better than a hot one as the gas key screws stretch out as they get heated up.
Once they stretch out, the leak gets large enough to cause cycling problems.
Short or replacement, one can remove the gas key and lap it on a surface plate to see if it's flat.
After the key is made flat, you lap the key into the carrier and assure that the carrier's seating surface is also flat.
Reassemble with rocksett between the key and the carrier and put in NEW screws and torque them to 50 inch-lbs followed by staking.

This is not a problem that will have anything to do with a gas block or needing to smooth out the movement of the bolt within the receiver.

[Sunday]

I would send it back to S&W before doing anything to it. They will take care of you.

+1

Clean it and do an inspection and trouble shoot if you are able and then if needed send it back to S@W.

[Hot Holster]

A big fat NEGATIVE on adding adjustable gas block. You paid for a working rifle, the manufacturer should provide you a working rifle... without you spending more money to make it work.

Elementary no?

Shoot some more to break it in further. If problem still persists call S&W customer service and get it sorted. It comes with a warranty for a reason.

This, and the advice of AR15barrels. Adding an adjustable gas block is not always an answer to fix problems, it's an addition to make a rifle perform functions the owner wants it to do.

[5gnut]

5gnut,
After doing this does you gun run reliably or do you still have frequent hang ups?

First time out, it was basically a single shot. Very disappointed, as I'm sure you were. After moving BCG back and for to wear rough spots it got a lot better. No jams until round #30 and has gotten better each time I have taken it out. Still get an occasional jam. Last time was at round #80. Give it some time. More fun breaking it I then sending back to S&W. Let me know how it works out.

[SDPAULIE]

Took about 200 rounds through mine to make it feed reliably. Had the exact same thing going on. I don't use the factory 10 round mag. 20 Round pmags are working well. After about 1000 rounds it will eat whatever I feed it.