AR feeding question

Encoreman said:

. . . it looked like the round wasn't feeding straight into the chamber. He said the bullet on some actually bent the brass at the mouth case.

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This description covers fully half of the different feeding issues that an AR can exhibit. We really need a picture.

Baring a picture, is the bolt face behind, or on top of the cartridge rim? That's a start. . .

Check the chamber thoroughly; it most likely is dirty enough to hang up, or there is some brass stuck in there somewhere. Also, bear in mind one man's idea of a clean gun isn't always the same as another's.
Magazine issues would be the other main cause. Trying different mags might reveal this. Also, the mag release not fully seated down (not screwed on enough) could cause the mag to back out after a couple rounds, but not necessarily fall out. This is an easy fix.

If the gun is truly clean and serviceable, it sounds like an ammunition or magazine issue.

Clean the gun like your life depended on it and seat the mag WITH FORCE. Don’t just gently press it in there, bleeping smack it.

1st step, reduce the mag load by 1 round (or 3). Second step, try a different mag.

Smacking an AR mag with force only exacerbates any problems with a mag.

The only time ARs have feed problems when dirty is if the AR is as filthy as a dirt road.

Encoreman, tell your son to replace the extractor spring with a Colt or Sprinco M4 spring.

Shoot a few then it chokes...If he grabs the charging handle and pulls it fully to the rear, then lets it fall free from his fingers, will it go through the entire mag without malfunction?

If yes, I’d try different ammunition.

If no, I would try a different mag.

Lots of things can attribute to this. Only three I have had issues with were an SK, a Ruger and a Jennings.
The SK and Ruger was after market mag issues. Cartridge would occasionally come up out of mag too soon. Bit of patience and reforming fixed that.
The Jennings just needed a good polishing of the ramp and entrance to chamber.
More history of the gun would help.
The age. Number of rounds through it.
Experience level of owner.
Did he try other than his mags?
Is the round jamming nose up or down?

I had the same or similar issue with a .300BLK. Some rounds would hit below the feed ramp or so low on the feed ramp that they would not glide up the feed ramp and into the chamber. After slowly cycling the rounds through the magazine I was able to detect what was happening. I changed magazines and the problem was resolved. The magazine I had been using either had bad geometry, bad springs, and/or some other issue in which the tips of the rounds weren’t reliably hitting the feed ramp.

I too am suspecting the magazine first. I had a brand new mag one time that was out of spec. Rounds would jump up into the charging handle area and get wedged by the bolt moving forward. New mag, no problems in that case.

Lets try the obvious first.

1. Clean the gun and the magazine (Yes, clean and lube the magazine body and spring)

1a. Clean the gas tube (check YouTube)
1b. Check the bolt Seal rings (3 of them)

2. Replace the magazine with a Pmag M2 or M3

3. Replace the extractor spring and add an extractor spring o-ring (BCM extractor o-ring upgrade)

We're getting ahead of ourselves, here. Have your son perform a lockback check to see if there AR is short stroking.

Insert an empty mag in the well and cycle the action by hand to make sure the mag will lock back the carrier. Place a single round in the mag, load the AR and fire it to make sure the carrier locks back. If it doesn't, the AR is short stroking.

When replacing the extractor spring, DO NOT use an O ring. If an extractor spring needs an O ring to work properly, the spring is weak and needs to be replaced with the correct spring. If an O ring is used with the correct spring, too much pressure is placed on the extractor. O rings deteriorate and fall apart. The pieces will cause problems with extraction. O rings were a temporary fix and only needed because the military refused to adopt the Colt M4 extractor for so long.

The correct springs are the Colt copper colored spring with black rubber insert and the Sprinco M4 spring with black rubber insert. Accept no substitutes.

You wrote he tried different ammo?
Was it factory?
If not try factory first.
If factory - what ammo? Bullet weight/form?
I'd try 55gn FMJ
Factory ammo with this specs should work in all ARs.
Next thing I'd look into: different mags.

MistWolf said:

Smacking an AR mag with force only exacerbates any problems with a mag.

The only time ARs have feed problems when dirty is if the AR is as filthy as a dirt road.

Encoreman, tell your son to replace the extractor spring with a Colt or Sprinco M4 spring.

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You can also get feed failures if the rifle doesn’t have enough lube.

I’ve seen multiple instances of FTFe that were resolved by simply adding lube.

I’ve also not seen a AR15 with too much extraction force. Too little, yes, but not too much.

BSW

briansmithwins said:

You can also get feed failures if the rifle doesn’t have enough lube.

I’ve seen multiple instances of FTFe that were resolved by simply adding lube.

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You're right, I've had it happen to me. Everytime it did, the AR was filthy. A little lube got it going again.

I’ve also not seen a AR15 with too much extraction force. Too little, yes, but not too much.

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The biggest problem is excessive force snapping the extractor over the rim. It can cause early extractor failure.

I've actually seen perfectly clean ARs not feed that were dry.

I help out at the pre-match orientation for a local rifle match and have had several people have rifles fail to feed during the shooting part of the orientation. The ones I'm thinking of had very clean internals that were bone dry. Simply adding lube got the rifles working again.

As a wise old man once told me: Oil and carbon is still a pretty good lube.

BSW

Lubricate the heck out of it with a good oil (not a high-solvent oil like Rem Oil, but something like Lucas gun oil, Militec, etc.); I personally use Mobil 1 5W30 EP for internals (not externals!) because I always have that on hand. Don’t forget to lubricate inside the bolt carrier. If it runs fine after this, it was underlubricated.

Other than making a mess, I don’t think you can overlubricate an AR with oil; excess will be slung out/blown out after a couple of rounds. A quality AR can usually run ok fairly dry, but they get more sensitive to fouling when dry.

I help out at the pre-match orientation for a local rifle match and have had several people have rifles fail to feed during the shooting part of the orientation. The ones I'm thinking of had very clean internals that were bone dry. Simply adding lube got the rifles working again.

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I’ve had that experience at carbine matches. A fellow shooter’s AR was experiencing repeated failures to feed, but after some oil on the bolt carrier and in the gas port vent holes, it ran perfectly the rest of the match.

Apart from what has been stated above another issue could be the gas system. Make sure the gas tube is not bent, the holes are not blocked, the gas key is working properly if it is not staked he needs to make sure the screws are not loose if they are they need to be torqued to 56 inch pounds. If there is a gas leak this causes a problem with bolt not having the proper dwell time needed to completely cycle and fully extract the spent cartridge and move all the way to the rear to pick up the next round. Too many variables without actual pictures at this point with given information .

I've been experimenting with Permatex AL anti seize. 1600 degree rated. Superb cohesive quality and smooth as silk.

briansmithwins said:

I've actually seen perfectly clean ARs not feed that were dry.

I help out at the pre-match orientation for a local rifle match and have had several people have rifles fail to feed during the shooting part of the orientation. The ones I'm thinking of had very clean internals that were bone dry. Simply adding lube got the rifles working again.

As a wise old man once told me: Oil and carbon is still a pretty good lube.

BSW

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Good points

MistWolf said:

Smacking an AR mag with force only exacerbates any problems with a mag.

The only time ARs have feed problems when dirty is if the AR is as filthy as a dirt road.

Encoreman, tell your son to replace the extractor spring with a Colt or Sprinco M4 spring.

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Perhaps. Lotta guys I’ve seen don’t seat the mag properly though so it could also help.

ms6852 said:

Make sure the gas tube is not bent, the holes are not blocked, the gas key is working properly if it is not staked he needs to make sure the screws are not loose if they are they need to be torqued to 56 inch pounds. If there is a gas leak this causes a problem with bolt not having the proper dwell time needed to completely cycle and fully extract the spent cartridge and move all the way to the rear to pick up the next round.

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Even IF they are staked, he should check...

I had a new AR - my first so I was somewhat clueless - that had the same issue as mentioned by the OP. At some point, I did check the gas key to see that it was staked and it was. And, I kept trying different ammo but with the same result.

Finally, even though they were staked, I checked the screws again to see if they were actually tight. They were not. Once torqued properly the gun ran like a champ with anything I fed it.

Holy cow! The lot need to dress yourselves up on failures. (Reducing the mag load?? Replacing extractor spring/o-ring? HUH??)

It’s either the magazine causing the round to nose dive, or you need to polish the ramps. (Check the ramps for a shard of metal on the edges)

THIS is what causes a round to jam, and case damage.

Bunch of voices here doing more harm than good.. oy-vey!