M&P 15 Sport Problem

[Dodobird1589]

i have an m&p15 sport i bought about four months ago. I am an experienced shooter but new to the AR platform. when shooting steel case(tula) and re-manufactured ammo through my sport it occasionally fails to fire, the bolt doesnt lock all the forward into battery. Is this something im doing wrong? just low powered crappy ammo? or a problem with the gun i can fix? it averages about one per 30 round pmag, sometimes less sometimes more. your help is much appreciated. ill have to take a pic of my sport to put up.

 

[Stebo]

You've probably done this already, but first a chamber cleaning. There might be some residue from the coating used on the steel ammo. Use a generous amount of your favorite cleaner, let it soak, and use a chamber brush. Break down, clean, and generously lube the BCG, insure the bolt gas rings are not aligned. Try a different mag. Use some decent brass ammo for a while, maybe you just need some breaking in.

Was this a new or used purchase? If used, check the buffer weight, stamped on the buffer face. If anything other than blank, this might be too heavy.

As a last, and worst possibility, you might have a partial gas system blockage, maybe a misaligned gas block. That would require a call to S&W CS for resolution, but try the other things first.

 

[oneyeopn]

and as we used to say in the old days "thats a big 10-4 on the lubrication" I also would recommend checking the buffer and spring. also there is a thread at the top under (I think its called) Notable Threads, the thread is tools I use to clean. It is by Japes. It is possible if you have a lot of carbon build up on your barrel extension locking lugs that the bolt may not always slide and lock into position. Just a few things to check. Welcome to the forum and yes we love PICS...it allows us to live vicariously through others...

 

[Dodobird1589]

I bought it brand new. All in all ive put about 300 rounds through it all **** ammo. Ive cleaned it twice. Granted im still learning how to clean my ar well but ive cleaned it twice and i keep my guns very clean. my thinking was maybe the ammo was just low powered and since the gun is new the buffer tube spring isnt broken in yet. When it fails to fire it also fails to extract the unfired round when i rack the bolt. Im assuming because the bolt didnt lock all the way into battery it doesnt grab the round.

 

[Stebo]

When it fails to fire it also fails to extract the unfired round when i rack the bolt. Im assuming because the bolt didnt lock all the way into battery it doesnt grab the round.

OK, I'll say it - Forward Assist! ...... Just kidding!

Your rifle should shoot anything, so I'd still suggest a really, really good cleaning, different mag, good ammo, and lube the &$/@ out of it.

 

[JaPes]

Maybe something is fouling the gas tube? Holding the upper muzzle end down, spray non-chlorinated brake cleaner down the gas tube to flush any fouling out the muzzle.

I've never had issues with TulAmmo in my AR's. You said you fired both TulAmmo and "Remanufactured" ammo. Did the failures happen with both types of ammo? What's the name of the commercial reloading company that produced the remanufactured ammo?

 

[Maddmax]

I've seen and felt some nasty feeling residue on some cheap steal cases. They were almost "sticky" to the touch and left "gunky" **** on your fingers when loading the mag.

I agree with all the above. Give it a super good cleaning (esp. the chamber). I'd give the BCG a good scrubing too. Then lube everything like the manual says.

 

[FromMyColdDeadHands]

It shouldn't be the TulAmmo. I have the exact same rifle,have put 500 rounds through it flawlessly. Be sure you run it pretty wet with oil.ARs love their oil.