M&P .308 issue need help

[towerdog]

First off Monday a call is going out to Smith and Wesson but wanted to see if any one here had any ideas. This is a buddy's rifle not mine.

When shooting one mag will run great then the same mag it will not eject and if it does eject it seem to not have enough power to chamber the next round. very important point is when it is acting up if it does eject the round the brass falls within inches of the rifle. when it is firing good the brass is being ejected at what I will call a normal throw from the extractor.

it is failing to operate correctly more than it is firing good. This is a brand new M&P AR .308, does with with several different brands of ammo and runs fine at time on the same ammo that didn't work a minute ago.

I was thinking the gas tube may e clogged but then it fires good some times?

Any ideas out there, thank you in advance for your time.

 

[rcmodel]

Check to see if the gas block on the barrel, or the gas key on the bolt carrier is loose.

rc

 

[towerdog]

Thank you RC

 

[Al Thompson]

Agree with RC. In any event my limited experience with S&W's customer service was very positive. Give'em a call.

 

[velocette]

Towerdog;
You do not say what kind of .308 ammo you are using. In my experience as a range officer at a large municipal range, the majority of problems with AR type rifles is when folks use steel cased ammunition. It commonly causes poor extraction, stuck cases, and poor cycling of the action.
If you have used steel cased ammo, the first thing to do is to thoroughly
clean the chamber with a brass brush and lots of solvent to remove the residue of the coatings on the steel cases. Then don't use steel cased ammo in your AR.

Roger

 

[towerdog]

So far we have fired several brands of brass from quality Hornady hunting rounds Remington, a couple of mil surplus brass, tula steel and federal brass too that I was there for.
By the way my AR has no issues with steel Tula or Silver Bear just clean it after every trip to the range as usual. I prefer brass but there for a while it was get what you can.

 

[towerdog]

Well the rifle is heading to S&W they have had a problem with some of the .308 AR's cycling. Thanks for the input guys I will update when the rifle returns and we get it to the range