Smith & Wesson M&P 10 not running

[South Bay Jim]

Hi Calgunners,
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 out and jam with the nose in the chamber and the bottom of the case pointing towards the mag with the BCG pressed against the center of the case so the round is at a 45 degree angle in the mag well and upper. It also will fail to lock back after the mag is empty 2 out of 3 times. I put about 70 rds of Winchester 7.62 x 51 and some cheap Walmart 7.62 x 51 made in Turkey and used the Factory mag and 2 Pmags and it does the same thing with any combo. I'm hoping that I won't have to go through the hassle of sending it back to S&W. I've had other AR platforms and know thar the BCG needs to be lubed well and did so before I went to the range and have since completely disassembled and lubed the crap out of it and applied gun grease to the bottom of the BCG anywhere that there was signs of ware and am hoping this will solve the problem. Has anyone had this happen or does anyone have any suggestions?

[Zartan]

Does it have an adjustable gas block?

[GM4spd]

Sounds like you have covered a lot of the usual suspects. The ammo you
are using has functioned in my own rifles with no issues. Sounds like a
lack of gas. Because the rifle is relatively new on the market there may
be no real expertise with it. I do know a guy who has one and his has run
fine. You may have to send it back to S&W,just my thoughts. Pete

[South Bay Jim]

No, it doesn't have an adjustable gas block but I considered that I may need to add one.

[ghostsup]

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

[TKM]

It's made to run with full pressure commercial 308.

Surplus 7.62x51 won't always get the job done.

[Mail Clerk]

Hi Calgunners,
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 out and jam with the nose in the chamber and the bottom of the case pointing towards the mag with the BCG pressed against the center of the case so the round is at a 45 degree angle in the mag well and upper. It also will fail to lock back after the mag is empty 2 out of 3 times. I put about 70 rds of Winchester 7.62 x 51 and some cheap Walmart 7.62 x 51 made in Turkey and used the Factory mag and 2 Pmags and it does the same thing with any combo. I'm hoping that I won't have to go through the hassle of sending it back to S&W. I've had other AR platforms and know thar the BCG needs to be lubed well and did so before I went to the range and have since completely disassembled and lubed the crap out of it and applied gun grease to the bottom of the BCG anywhere that there was signs of ware and am hoping this will solve the problem. Has anyone had this happen or does anyone have any suggestions?

South Bay Jim,

I had a similar experience with my AR 556/223 rifle in which I had the same symptoms you describe.

After taking mine in to a smith it turned out to be a gas leak in the carriers "gas key". It turned out for me I had to rebuild my entire BCG and saving the bolt itself and other parts. I replaced the entire bolt carrier and put it back together. When I took it out to the range my rifle ran like a race horse!!! Very happy camper I was

For you I would take it to a smith and have him torque down the bolts on the key and re-stake them in place. They might be loose. Try that first and see what happens. If that doesn't work then you might consider doing the same as I did.

Good luck,

Mail Clerk

[shafferds]

Also bad chamber

[PSLguy]

I own an M&P 10 and it has been 100% reliable. One thing to check is if the gas block is properly aligned with the port in the barrel. Just remove it and rei-install which is easy to do. I replaced mine with a low profile one when I put on a free float rail. The railed gas block it comes with was pretty easy to remove.

Key to easy removal is to use the proper size punch (5/64) and drive it out from right side to left side. In other words, it should come out the left side of the barrel. Trying to remove it the other way is extremely difficult if not impossible. This is the opposite of most other gas blocks.

Mine came out easy with a few sharp raps with a hammer. Don't try to use cheap Harbor Freight punches as they are not tempered and will just bend. Home Depot carries quality, US made punches in the hardware section. They are light blue colored but I can't remember the brand name.

[LBDamned]

I own an M&P 10 and it has been 100% reliable. One thing to check is if the gas block is properly aligned with the port in the barrel. Just remove it and rei-install which is easy to do. I replaced mine with a low profile one when I put on a free float rail. The railed gas block it comes with was pretty easy to remove.

Key to easy removal is to use the proper size punch (5/64) and drive it out from right side to left side. In other words, it should come out the left side of the barrel. Trying to remove it the other way is extremely difficult if not impossible. This is the opposite of most other gas blocks.

Mine came out easy with a few sharp raps with a hammer. Don't try to use cheap Harbor Freight punches as they are not tempered and will just bend. Home Depot carries quality, US made punches in the hardware section. They are light blue colored but I can't remember the brand name.

are you referring to the gas tube?... The gas block itself is clamp style with Allen screws...

if he's just re-aligning the gas block, there isn't anything to drive out with a punch.

[Diesel12]

Does it have an adjustable gas block?

This ^^, get an adjustable gas block and your extraction issues will disappear.

[major burnout]

If you bought a new rifle, rough surfaces might be to blame. Drop the mag and exercise the bolt a hundred times or so. This will knock down some of the rough edges.

[PSLguy]

are you referring to the gas tube?... The gas block itself is clamp style with Allen screws...

if he's just re-aligning the gas block, there isn't anything to drive out with a punch.

HA!!!! You're right. I'm at work and mis-remembered which gun it was that had the odd gas block pin. Sorry about that.

[GM4spd]

It's made to run with full pressure commercial 308.

Surplus 7.62x51 won't always get the job done.

Ran ok on German 762NATO in one report I read. Pete

[randomBytes]

My M&P 10 runs fine with NATO ammo (American Eagle I think),
my son had 2 fail to feed issues but it runs like a watch for me.