Hi everybody, I tried looking around on the site to help with my issue but haven't found anything yet. I have an M&P 15 Sport and it is failing to feed completely. What is happening is about every 3rd-5th round it loads a round into the chamber but only 3/4 of the way into the chamber and stops. The BCG and bolt stops short. The round is not hung up but actually in the chamber. It is new, only 50 rounds through it. Only 50 cause constantly going to the charging handle every 3-5 rounds gets old. Using PMC .223 rounds. It became more apparent of this issue the more it was shot, started around 10th round, then 6th, then 3rd, and kept going on the 3rd roughly. I cleaned it and lubricated where needed before going out shooting. So thoughts of fixes? I haven't noticed anything really rough, nothing is hanging up when I am messing with it, but something is. Any ideas for me to do would be awesome. Thank you.

What ammo are you shooting?

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SFC, US Army, Retired

PMC Bronze .223. They work fantastic in my custom .223 I built myself.

PMC Bronze is marginal in my opinion. First thing I'd do is try other ammo - preferably something like M193 or 855. I'd guess that once you get some miles on the rifle it will probably work fine with PMC, but that PMC Bronze is .223 and not true 5.56. My opinion.

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Roger
USN, Retired, NRA Lifer

Ok to get to the obvious question that I am obliged to ask...Did you field strip, inspect, clean, & lube it prior to it's 1st range outing? Most likely the answer is yes.

From your post, I infer that you've built a .223 AR yourself, so you'll know what I'm going to say next. Separate the upper from the lower. Pull the BCG. Check everything for unusual witness marks that would indicate that the bolt is binding in the upper. If the bolt is binding in the upper on a brand new AR, the witness marks should be very evident.

Next thing I would do is to inspect the PMC bronze rounds from a single box for consistency. Do they all look to be the same overall length. Do all the projectiles appear to be consistently seated?

After that, think about your range session. Compared to shooting PMC Bronze out of your custom .223 AR-15 to the M&P, did the recoil impulse from the M&P feel softer? If so, this could indicate a production flaw in the ammunition.

If all else fails... call S&W customer service. The best part of owning a S&W M&P is the product service policy.

Good luck!

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-John

I did field strip, checked everything out closely. I didn't see anything out of the ordinary. Ill try some different ammo and see what happens. The recoil did feel different but not enough to be bothersome. In my other AR I am running a bravo company heavy buffer and sprinco blue spring. I'm not sure what the sport is.

All the rounds look the same and sound the same(shaken to judge the amount of powder). What I did notice is going on the charging handle when it did hit the BCG it was stiff to come back fully.

They're not to bad for the price, I would suggest to start clean and lube, I run mine a little wet, second, you suggested you might be getting some bolt binding in the raceway, check for "witness marks" on the bolt carrier and the frame rails, as well as any possible binding in the plunger tube, and the low round count makes it likely/possible that it needs to be broken in, you can expedite that process by running the rifle another 50 to 100 cycles by hand with the op rod, no need to let is slam into battery, allow it to operate just fast enough so that it returns to battery, and did I say "lube it" the lube will also carry away any debris loosened up by the cycling.

Then change the magazine, I would try to cycle by hand first, I had a first round flyer three to five inches out of the main group with 55 grain PMC, I was running a five round ASC steel magazine, tried a 30 round Troy and the flyer was gone, but I had rounds popping out of the Troy before they were in battery. 20 round Colt mags and I was very close to MOA, switched to 62 grain PMC Green Tip and sub MOA, down to 1/2 inch.

Then you can play with ammo if that doesn't work, but I bet its the magazine, they vary widely in fit and function, the Colt mags are the old ones with the aluminum follower???

Currently I am running PMAGs but I have some others around. Give that a shot as well. I rechecked it again and there is no witness marks what so ever. I just lubed and oil it down really well. I will find out this weekend on what is going on and will update if my problem persists or is resolved.

I have owned this rifle for around 3 years and have been to the range with it a few times and have run around 300 rounds through it of M855 and 193 ammo. Last trip to the range it started to fail to feed. I had some oil with me so I pulled out the bolt carrier and did a field strip and wiped down the bolt well and oiled it well. Still failed to feed, the bolt was not coming back far enough to pick up the next round and would dig into the round in the mag and stop.
I thought it was a dirty gun or dirty ammo so I went home and cleaned it really thoroughly, oiled it and put it back together.
Today I took it to the range again and after 50 rounds it started doing the same thing. I again had oil and a clean rag so I cleaned the bolt carrier and bolt and lubed them up to the point oil was dripping off the locking lugs. It didn't complete two rounds and did the same thing. I am wondering if there is a way to adjust the gas block or if there may be something in the gas system causing this. I have found nothing about the gas system on this rifle, though I know it is something in the M16 which can be adjusted, I remember having to adjust it when there was an operation problem, like fail to feed.
I have tried 10 and 20 round steel mags as well as the PMAG it came with and no changes. I have tried Remington and Winchester .556 fmj and there is no change what so ever. After a mag or maybe a two mags it starts doing the same thing, the bolt carrier is not moving far enough back to pickup the next round.

OK, there is no adjustment in the AR gas system if you have the standard front sight tower. The US military doesn't like adjustable gas systems since bored troops will play with the adjustments. Sights included.

I'd suggest just to cover everything that you get a can of brake kleen, gum cutter or other aerosol solvent and hose out the gas tube and the gooseneck on the stripped bolt carrier. This should take care of any possible minor obstruction in the gas system.

Now then, look at the bolt. Have you got 3 gas rings? If you have just the bolt (no cam pin) in the carrier, do the gas rings have enough tension to support the weight of the bolt?

Finally, pull the recoil spring and buffer. Make sure they're correct and in good condition.

Re-read post #1 to see if I missed anything. If you bought it new, forget everything I typed above: call customer service at the factory and send that puppy back!