new AR15, failure to feed issues

Well two things changed, the ammunition and the magazine. Personally I would look first at the magazine and using the Winchester white box stuff try using the magazine which previously worked. That will save you tweaking and peaking on the rifle trying to see if it can be made to work with the Winchester ammunition. I would start there, with a magazine you know worked. Then worry about the ammunition.

Ron

Reloadron said:

Well two things changed, the ammunition and the magazine. Personally I would look first at the magazine and using the Winchester white box stuff try using the magazine which previously worked. That will save you tweaking and peaking on the rifle trying to see if it can be made to work with the Winchester ammunition. I would start there, with a magazine you know worked. Then worry about the ammunition.

Ron

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Agreed, one variable at a time man.

If the bolt is locking back on the last round, I'd blame the magazine, if not I'd blame the ammo.

I'm pretty picky about ammo, so I'd just avoid the WWB in the future, and stick to what works. If I had problems with a wider range of ammo, I'd be looking at things like rings and buffers

SPORTS, man!
As mentioned, check one thing at a time, the magazine is simpler to check.

https://www.armystudyguide.com/cont..._common_tasks/correct-malfunctions-of-a.shtml

Rare to have factory ammo malfs with an AR. As stated above, go back to your original mags.....after numbering all of them. Silver Sharpies work well for me.

Next time you have the same issue, it would help to have pictures. But as everyone has suggested eliminate one problem at a time. Majority of the time the culprit is the magazine. I would load all the magazines as you did for your training and see how the rounds seat in each of the magazines, eject rounds with your thumb and notice the angle of the rounds as the next one move up to the top of the magazine. The follower on one of the magazines or the spring could be out of spec.

Check the
Buffer and buffer tube, also check the bolt orings final check the mags

MrBitey said:

Is the idea that if the bolt isn't locking back on an empty mag then there's a problem with cycling, which could be due to the ammo? The gun was locking back fine on empty mags, and the instructors did suspect the problem could be with one of the mags. But I didn't have my mags numbered and the drills involved a lot of mag changes, so I can't say whether failures were isolated to a particular mag. I hope to get back and re-test tomorrow.

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Usually, if the bolt locks back on an empty mag, you can assume that the ammo is adequate and is charged enough to create enough gas to blow back the BCG fully to the rear and either local back on an empty mag or catch a fresh round from a charged magazine. If the bolt wasn’t locking back on an empty mag, it would be indicative of underpowered ammo which can induce malfunctions by not causing enough rearward travel of the BCG to clear the magazine and chamber a new round. Not locking back on an empty mag could also indicate a bad follower which is not common.

Your problem could also be related to the gas system if it failed to lock back on an empty mag. Perhaps the gas port is too small or obstructed. Generally, this is not common, but I once bought a barrel that had a slightly undersized gas port and was causing fits till I opened it up ever so slightly.

jonnyc said:

Rare to have factory ammo malfs with an AR. As stated above, go back to your original mags.....after numbering all of them. Silver Sharpies work well for me.

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On the largest AR forum on the internet, factory ammo malfs with cheap white box are the #1 reported problem. The top three issues are ammo, mags, and operator error, which also controls the selection of the first two. An AR15 is based on the mil spec, which requires full power NATO ammo, and DOD doesn't offer 87 different loads by dozens of ammo makers of which a large quantity is made as cheap as possible.

It goes to gun testers using it to see if it really is a milspec gun - some makers will play with port sizing and increase it to run cheap low powered fodder. That tends to run the pressure up and also create problems with cycling speeds, which can actually prevent ejection and cause double feeding when NATO is used. An AR is not like a gas operated shotgun with metering valves which compensate for light and heavy loads in the same tube alternately - a gun tester method of stressing the gun during a review. Nope, milspec AR's are to be fed milspec ammo only, by design intent and policy. Don't want no guns chokin in the battlefield. The idea that" it should run on whatever you feed it" was not part of Stoner's engineering. If so, then an adjustable gas valve would be on it, like battle rifles from the 60's. They were used with rifle grenades then, the M16 got an underslung launcher.

Avoid white box unless you like lots of malfunction drills, find NATO rated and it will function a lot better.

Tirod said:

Avoid white box unless you like lots of malfunction drills, find NATO rated and it will function a lot better.

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I don’t know man, when I build an AR it needs to shoot from Range pick up/dig out russian steel ammo with rust to black hills match grade ammo.

sure sure I’m exaggerating a little, but does needs to run the cheap stuff.

I have one that hates steel case and it just happens to be an original Colt from the early 70s, I still don't know why, all the others eat anything thrown at them, I also would check your mags 1st, I've seen reloads and factory reloads cause problems but rarely factory ammo. I had some 42rnd mags purchased at Academy that needed a little polishing on the lips and after that worked flawlessly, a little polishing compound and a shotgun mop.

Not too many ARs ship under gassed or with more than a Carbine buffer, and the OP’s also comes standard with a semi-carrier. You’d need pretty weak ammo to not cycle the bolt, though I won’t vouch for WWB.

I would vouch for Magpul, again no one is perfect but following the logical path to elimination magazines ought to be swapped.

I am unfamiliar with the rifle manufacturer beyond a quick spec check of your model so a few things to look over. BCG, run the basics to make sure rings are good. Buffer, remove it and inspect it and receiver extension for damage.

If everything is in order, bring that WWB and another brand of ammo along with your old and new marked mags on range day.

MrBitey said:

The gun would fire and start to feed a new round, but the new round would jam up at an angle with little forward movement (i.e. the entire round was visible through the ejection port)…

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It’s your extractor spring. Replace it with a Colt extractor spring.

Don’t over complicate it. Check the magazines

MrBitey said:

Is the idea that if the bolt isn't locking back on an empty mag then there's a problem with cycling, which could be due to the ammo? The gun was locking back fine on empty mags, and the instructors did suspect the problem could be with one of the mags. But I didn't have my mags numbered and the drills involved a lot of mag changes, so I can't say whether failures were isolated to a particular mag. I hope to get back and re-test tomorrow.

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Yes. Bargain ammo tends to be underpowered, which makes for short stroking, which means it won't lock back on the last round. This is especially common with a new rifle, where the parts haven't quite worn in to a better fit, and is often compounded by insufficient lube. With a new build, I like to run it really wet, and I use full power 5.56 ( I stick to Federal Lake City M855 for the first 200 rounds or so).

Thanks for sharing your results.

Ron

MrBitey said:

I'm curious what led you to suspect the extractor!

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This statement right here-

MrBitey said:

The gun would fire and start to feed a new round, but the new round would jam up at an angle with little forward movement (i.e. the entire round was visible through the ejection port).

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Experience troubleshooting ARs shows that when this malfunction reads its ugly head, it’s a bad extractor spring.

Armalites are very clip sensitive.

Try some good USGI magazines and quality ammo.

It will solve your issues.

It's a good idea to number your magazines. Some times a specific mag causes problems.

I’m betting it’s the Winchester White box. Not great ammo.
There’s been some discussion that the WWB sold at Walmart is a lower grade. I can’t confirm that, but I’ve read that more than once, and a co-worker with a Taurus Judge swore that WWB from Walmart wouldn’t eject and had to be knocked out with a dowel but WWB from other stores would.
Magpul mags are pretty reliable.
Did you clean & lube it?

Check the feed ramp, ammo and mags