Can you diagnose this feeding problem?

[DrMikeinPDX]

My new M&P 15 Sport 2 has a weird feeding problem. It seems to feed military ammo OK, but civilian .223 ammo gets damaged in the feeding process and about 12% of the rounds won't chamber completely.

I took the photo above with a macro lens.

Has anyone seen this kind of cartridge damage before? Any idea what is causing that? I can't quite visualize the mechanical process that would do that.

My round count is at 300 and I've cleaned/lubed it twice. It's in pieces now soaking in CLP.

Thanks in advance!

Mike near Portland

 

[LVSteve]

What brand of .223 is my first question.

If it cycles and feeds NATO surplus OK, then the damage suggests that the .223 isn't cycling the bolt all the way back in the same way. The round is coming out of the magazine and the bolt is riding over the top, chewing up the case and dislodging the bullet.

 

[DrMikeinPDX]

Thanks LV Steve! That sounds like a reasonable conclusion.

I tried about 5 different brands of .223 and four different Magpul mags. All had various percentages of damaged rounds, but overall I'd say about 12% failed to chamber and fire. I don't know if it is significant, but the first round of each mag always fed correctly. And as I mentioned before, military 5.56 ammo functioned 100% Maybe it's loaded a bit hotter? A friend says the military brass is thicker, maybe that's a factor.

As a new AR owner, I was a bit disturbed to see that the hammer would fall without the bolt being completely closed, but apparently that's not a big issue in the AR world. It did help me learn the "mortar maneuver" for removing a stuck cartridge.

I just completed my third thorough clean and lube (did not remove extractor) and will return to the range for more testing in a few days.

Other than this feeding problem, I'm impressed with this little carbine. I just hope I can get it to work reliably.

Mike near Portland

 

[JWF III]

Will the bolt lock back on the last round of 223?

I tend to agree with LVSteve. Likely a condition known as under gassed. Did you buy this rifle new or used? If used, the previous owner may have monkeyed with something. (Changed gas blocks and didn’t get lined up correctly. Installed a heavier buffer. Etc.) If you bought it new, send it back. Gas lock is the most likely culprit.

One thing you could try is removing the gas tube. Check for and remove any debris. With 5.56 functioning normally, I doubt you’ll find anything, but it”s someth8ng relatively easy to check.

Under gassed is an extremely rare problem in a factory gun. Over gassed is much more common, with several of the same symptoms.

Wyman

 

[cyphertext]

We've seen this before... send it back to S&W. Your bolt is out of spec. They will replace the bolt, possible the complete BCG (don't remember exactly)... but I do remember seeing bent rounds and bolt replacement from S&W.

 

[DrMikeinPDX]

Thanks guys,

I did buy it new.

I hosed the gas tube with Break Free "Powder Blast" solvent today as part of a full clean and lube. Maybe that will help.

I'm taking it to the range one more time with some .223 and some 5.56. If it still malfunctions, it is going back to S&W.

Still open to ideas if someone else wishes to contribute.

Take Care,

Mike near Portland

 

[vonn]

Please keep us posted on the resolution of your problem.

 

[DrMikeinPDX]

Bent Rounds M&P 15

Thanks guys! I searched on the term "bent rounds" and found several cases of M&P 15 owners with this problem going back several years. It seems that sending it in for bolt replacement is the way to go. It also does not speak well for S&W quality control if they are still having this problem crop up.

I used the contact form on the S&W site to ask them for advice. They say they will respond in 3-5 days.

Will keep you guys posted!

Mike near Portland

 

[noro]

Dr Mike,

You could call S&W direct for a faster response. More than
likely, the'll send you a ticket to return it. If you don't mind
waiting, its the way to go with the warranty.

Mine had the bolt carrier group replaced at 1500 rounds and
runs fine now at no cost to me. The gas key screws had cracked
and caused a large gas leak.

You can read the whole post "M&P15 short stroking" here on
the forum.

 

[blues7]

I had the bolt replaced, (out of spec), after the second round failed to properly feed, got bent, and was a bear to remove before sending the rifle back to S&W.

S&W sent me a return label and had it back to me a week to the day later. All has been well since.

I believe only the bolt was replaced, not the entire BCG, but I can't swear to it.

 

[Rastoff]

I hope S&W gets it fixed up for you.

That is what rounds typically look like when involved in a double feed. Did you have any of those?

 

[DrMikeinPDX]

I hope S&W gets it fixed up for you.

That is what rounds typically look like when involved in a double feed. Did you have any of those?

No double feeds. I would note that the bolt *almost*closed on the bent rounds. I'm new to the AR platform and freaked out a little when I realized the hammer would drop when the bolt wasn't quite closed!

No response yet from S&W. I may call them tomorrow if they don't respond to my inquiry.

Take Care,

Mike

 

[DrMikeinPDX]

Bent Rounds = New Bolt

OK, friends the problem is fixed. S&W service got it back to me in a little over three weeks. They paid the shipping each way, I just had to find a box to pack it in.

The repair order says they replaced the bolt.

Today I put 150 rounds of mixed factory ammo through it and everything worked fine!!

So if someone finds this thread while searching for "bent rounds Smith & Wesson M&P 15" please be advised that no amount of cleaning and break in will fix the problem. Just call S&W on the phone. Don't bother with the online service form. They will get it fixed for you.

I have no idea what is wrong with the bolts that cause this problem, but one might think that S&W could find a better supplier for their bolts. This problem has been reported for several years.

Mike

 

[vonn]

Thanks for the update. Glad you are up and shooting!

 

[noro]

Dr. Mike,

Glad it worked out for you. It seems to work out much better
calling S&W should problems arise, especially with modern
weapons that have the warranty. They are much quicker to
respond.

With the bolts, I don't think its a bolt problem exactly but more
than likely the gas key or gas key screws. I noticed that the
screws were staked on the sides rather than the top on the new
BCG they put into mine.

S&W does a great job in dealing with warranty problems (JMHO)
You could have thrown parts at it yourself and got it working
faster but why when you have the warranty and don't mind
waiting?

 

[blues7]

I was told by my rep a few years back when I sent mine back after firing one round that the bolt was out of spec. Apparently a milling issue, for lack of a better or more specific term.


ETA: If I recall correctly, the rep told me that the imperfection was on the bolt face near the extractor pocket.

 

[cyphertext]

Glad you are up and running... as far as S&W quality, this happens to other manufacturers as well. I don't know who S&W sources their bolts from today, but back when I bought mine, they sourced from Microbest. Microbest makes bolts for government contracts and many other OEMs.

Search Colt and you will find the bent bullets happening with their rifles too... It happens. Sucks when it does happen to you, but if their customer service takes care of it right away, you can't ask for much more.

 

[touchoneoff]

DrMike, glad they got your rifle squared away!